CVE-2026-23409
published 2026-04-01CVE-2026-23409: In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loops to be…
PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.18%
7.5th percentile
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix differential encoding verification
Differential encoding allows loops to be created if it is abused. To
prevent this the unpack should verify that a diff-encode chain
terminates.
Unfortunately the differential encode verification had two bugs.
1. it conflated states that had gone through check and already been
marked, with states that were currently being checked and marked.
This means that loops in the current chain being verified are treated
as a chain that has already been verified.
2. the order bailout on already checked states compared current chain
check iterators j,k instead of using the outer loop iterator i.
Meaning a step backwards in states in the current chain verification
was being mistaken for moving to an already verified state.
Move to a double mark scheme where already verified states get a
different mark, than the current chain being kept. This enables us
to also drop the backwards verification check that was the cause of
the second error as any already verified state is already marked.
Affected
29 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.1.164-1 (bookworm) | linux 6.1.164-1 (bookworm) |
| linux | linux | — | — |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84 | ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84 |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 1439150cd3c411228b387ab5efca92199d2a659a | 1439150cd3c411228b387ab5efca92199d2a659a |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 0fab44285445e9012674396d5c1236a67da518e0 | 0fab44285445e9012674396d5c1236a67da518e0 |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a | f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4a |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 34fc60b125ed1d4eb002c76b0664bf0619492167 | 34fc60b125ed1d4eb002c76b0664bf0619492167 |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 623a9d211bbbb031bb1cbdb38b23487648167f8a | 623a9d211bbbb031bb1cbdb38b23487648167f8a |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 1ff4857fac56ac5a90ee63b24db05fa5e91a45aa | 1ff4857fac56ac5a90ee63b24db05fa5e91a45aa |
| linux | linux | >= 031dcc8f4e84fea37dc6f78fdc7288aa7f8386c3 < 39440b137546a3aa383cfdabc605fb73811b6093 | 39440b137546a3aa383cfdabc605fb73811b6093 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 5.10.251-1 | 5.10.251-1 |
| linux | linux_kernel | >= 0 < 6.1.164-1 | 6.1.164-1 |
| linux | linux_kernel | >= 0 < 6.12.74-2 | 6.12.74-2 |
| linux | linux_kernel | >= 0 < 6.19.6-2 | 6.19.6-2 |
| linux | linux_kernel | >= 4.17.1 < 5.10.253 | 5.10.253 |
| linux | linux_kernel | >= 5.11 < 5.15.203 | 5.15.203 |
| linux | linux_kernel | >= 5.16 < 6.1.169 | 6.1.169 |
| linux | linux_kernel | >= 6.13 < 6.18.18 | 6.18.18 |
| linux | linux_kernel | >= 6.19 < 6.19.8 | 6.19.8 |
| linux | linux_kernel | >= 6.2 < 6.6.130 | 6.6.130 |
| linux | linux_kernel | >= 6.7 < 6.12.77 | 6.12.77 |
| ubuntu | linux-azure-5.15 | — | — |
| ubuntu | linux-azure-5.4 | — | — |
CVSS provenance
nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.2HIGH
vendor_ubuntu7.8HIGH
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Ubuntu
Linux kernel (Xilinx) vulnerabilities
vendor_ubuntu·2026-05-07·CVSS 6.4
CVE-2025-68288 [MEDIUM] Linux kernel (Xilinx) vulnerabilities
Title: Linux kernel (Xilinx) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Josh Eads, Kristoffer Janke, Eduardo Vela Nava, Tavis Ormandy, and Matteo
Rizzo discovered that some AMD Zen processors did not properly verify the
signature of CPU microcode. This flaw is known as EntrySign. A privileged
attacker could possibly use this issue to cause load malicious CPU
microcode causing loss of integrity and confidentiality. (CVE-2024-36347)
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation,
Ubuntu
Linux kernel (Azure) vulnerabilities
vendor_ubuntu·2026-05-07·CVSS 7.8
CVE-2025-22058 [HIGH] Linux kernel (Azure) vulnerabilities
Title: Linux kernel (Azure) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corre
Ubuntu
Linux kernel (BlueField) vulnerabilities
vendor_ubuntu·2026-04-29·CVSS 4.7
CVE-2022-48875 [MEDIUM] Linux kernel (BlueField) vulnerabilities
Title: Linux kernel (BlueField) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update c
Ubuntu
Linux kernel (Azure) vulnerabilities
vendor_ubuntu·2026-04-22·CVSS 4.7
CVE-2026-23410 [MEDIUM] Linux kernel (Azure) vulnerabilities
Title: Linux kernel (Azure) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corre
Ubuntu
Linux kernel (Raspberry Pi) vulnerabilities
vendor_ubuntu·2026-04-20·CVSS 4.7
CVE-2025-40215 [MEDIUM] Linux kernel (Raspberry Pi) vulnerabilities
Title: Linux kernel (Raspberry Pi) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- x86 architecture;
- GPIO subsystem;
- GPU drivers;
- BTRFS file system;
- XFRM subsystem;
- IPv4 networking;
- IPv6 networking;
Ubuntu
Linux kernel (Azure) vulnerabilities
vendor_ubuntu·2026-04-13·CVSS 7.8
CVE-2024-53114 [HIGH] Linux kernel (Azure) vulnerabilities
Title: Linux kernel (Azure) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corre
Ubuntu
Linux kernel (Azure FIPS) vulnerabilities
vendor_ubuntu·2026-04-09·CVSS 7.8
CVE-2025-21833 [HIGH] Linux kernel (Azure FIPS) vulnerabilities
Title: Linux kernel (Azure FIPS) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update
Ubuntu
Linux kernel (Azure FIPS) vulnerabilities
vendor_ubuntu·2026-04-09·CVSS 7.8
CVE-2025-71125 [HIGH] Linux kernel (Azure FIPS) vulnerabilities
Title: Linux kernel (Azure FIPS) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update
Ubuntu
Linux kernel (Intel IoTG Real-time) vulnerabilities
vendor_ubuntu·2026-04-09·CVSS 7.8
CVE-2026-23410 [HIGH] Linux kernel (Intel IoTG Real-time) vulnerabilities
Title: Linux kernel (Intel IoTG Real-time) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026-23403,
CVE-2026-23404, CVE-2026-23405, CVE-2026-23406, CVE-2026-23407,
CVE-2026-23408, CVE-2026-23409, CVE-2026-23410, CVE-2026-23411)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
Th
Ubuntu
Linux kernel (OEM) vulnerabilities
vendor_ubuntu·2026-04-06·CVSS 7.2
CVE-2026-23404 [HIGH] Linux kernel (OEM) vulnerabilities
Title: Linux kernel (OEM) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD Zen 5 processors supporting RDSEED
instruction did not properly handle entropy, potentially resulting in the
consumption of insufficiently random values. A local attacker could
possibly use this issue to influence the values returned by the RDSEED
instruction causing loss of confidentiality and integrity. (CVE-2025-62626)
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibl
Red Hat
kernel: apparmor: fix differential encoding verification
vendor_redhat·2026-04-01
CVE-2026-23409 CWE-372 kernel: apparmor: fix differential encoding verification
kernel: apparmor: fix differential encoding verification
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix differential encoding verification
Differential encoding allows loops to be created if it is abused. To
prevent this the unpack should verify that a diff-encode chain
terminates.
Unfortunately the differential encode verification had two bugs.
1. it conflated states that had gone through check and already been
marked, with states that were currently being checked and marked.
This means that loops in the current chain being verified are treated
as a chain that has already been verified.
2. the order bailout on already checked states compared current chain
check iterators j,k instead of using the outer loop iterator i.
Meaning a step backwards in states
Debian
CVE-2026-23409: linux - In the Linux kernel, the following vulnerability has been resolved: apparmor: f...
vendor_debian·2026
CVE-2026-23409 CVE-2026-23409: linux - In the Linux kernel, the following vulnerability has been resolved: apparmor: f...
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loops to be created if it is abused. To prevent this the unpack should verify that a diff-encode chain terminates. Unfortunately the differential encode verification had two bugs. 1. it conflated states that had gone through check and already been marked, with states that were currently being checked and marked. This means that loops in the current chain being verified are treated as a chain that has already been verified. 2. the order bailout on already checked states compared current chain check iterators j,k instead of using the outer loop iterator i. Meaning a step backwards in states in the current chain verification was being mistaken for m
VulDB
Linux Kernel up to 7.0-rc3 apparmor encoding error (EUVD-2026-17839 / WID-SEC-2026-0950)
vuldb·2026-04-19
CVE-2026-23409 [CRITICAL] Linux Kernel up to 7.0-rc3 apparmor encoding error (EUVD-2026-17839 / WID-SEC-2026-0950)
A vulnerability was found in Linux Kernel up to 6.6.129/6.12.76/6.18.17/6.19.7/7.0-rc3 and classified as critical. The affected element is an unknown function of the component apparmor. The manipulation results in encoding error.
This vulnerability is cataloged as CVE-2026-23409. The attack must originate from the local network. There is no exploit available.
It is suggested to upgrade the affected component.
OSV
linux-oem-6.17 vulnerabilities
osv·2026-04-06·CVSS 7.2
CVE-2025-62626 [HIGH] linux-oem-6.17 vulnerabilities
linux-oem-6.17 vulnerabilities
It was discovered that some AMD Zen 5 processors supporting RDSEED
instruction did not properly handle entropy, potentially resulting in the
consumption of insufficiently random values. A local attacker could
possibly use this issue to influence the values returned by the RDSEED
instruction causing loss of confidentiality and integrity. (CVE-2025-62626)
Qualys discovered that several vulnerabilities existed in the AppArmor
Linux kernel Security Module (LSM). An unprivileged local attacker could
use these issues to load, replace, and remove arbitrary AppArmor profiles
causing denial of service, exposure of sensitive information (kernel
memory), local privilege escalation, or possibly escape a container.
(LP: #2143853, CVE-2026-23268, CVE-2026-23269, CVE-2026
OSV
CVE-2026-23409: In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loop
osv·2026-04-01
CVE-2026-23409 CVE-2026-23409: In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loop
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix differential encoding verification Differential encoding allows loops to be created if it is abused. To prevent this the unpack should verify that a diff-encode chain terminates. Unfortunately the differential encode verification had two bugs. 1. it conflated states that had gone through check and already been marked, with states that were currently being checked and marked. This means that loops in the current chain being verified are treated as a chain that has already been verified. 2. the order bailout on already checked states compared current chain check iterators j,k instead of using the outer loop iterator i. Meaning a step backwards in states in the current chain verification was being mistaken for m
GHSA
GHSA-53jf-v56h-xgqg: In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix differential encoding verification
Differential encoding allows lo
ghsa_unreviewed·2026-04-01
CVE-2026-23409 GHSA-53jf-v56h-xgqg: In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix differential encoding verification
Differential encoding allows lo
In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix differential encoding verification
Differential encoding allows loops to be created if it is abused. To
prevent this the unpack should verify that a diff-encode chain
terminates.
Unfortunately the differential encode verification had two bugs.
1. it conflated states that had gone through check and already been
marked, with states that were currently being checked and marked.
This means that loops in the current chain being verified are treated
as a chain that has already been verified.
2. the order bailout on already checked states compared current chain
check iterators j,k instead of using the outer loop iterator i.
Meaning a step backwards in states in the current chain verification
was being mistaken
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/0fab44285445e9012674396d5c1236a67da518e0https://git.kernel.org/stable/c/1439150cd3c411228b387ab5efca92199d2a659ahttps://git.kernel.org/stable/c/1ff4857fac56ac5a90ee63b24db05fa5e91a45aahttps://git.kernel.org/stable/c/34fc60b125ed1d4eb002c76b0664bf0619492167https://git.kernel.org/stable/c/39440b137546a3aa383cfdabc605fb73811b6093https://git.kernel.org/stable/c/623a9d211bbbb031bb1cbdb38b23487648167f8ahttps://git.kernel.org/stable/c/f90e3ecd9e1ed69f1a370f866ceed1f104f3ab4ahttps://git.kernel.org/stable/c/ff7c73744fafe944ed9a7b2b7cf6c8d5557a3d84
2026-04-01
Published