CVE-2025-68807
published 2026-01-13CVE-2025-68807: In the Linux kernel, the following vulnerability has been resolved: block: fix race between wbt_enable_default and IO submission When wbt_enable_default() is…
PriorityP422medium6.4
EPSS
0.15%
5.2th percentile
In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.
The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:
rq_wait[0]:
inflight: -1
has_waiters: True
rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter
will become negative.
And results in hung task warnings like:
task:kworker/u24:39 state:D stack:0 pid:14767
Call Trace:
rq_qos_wait+0xb4/0x150
wbt_wait+0xa9/0x100
__rq_qos_throttle+0x24/0x40
blk_mq_submit_bio+0x672/0x7b0
...
Fix this by:
1. Splitting wbt_enable_default() into:
- __wbt_enable_default(): Returns true if wbt_init() should be called
- wbt_enable_default(): Wrapper for existing callers (no init)
- wbt_init_enable_default(): New function that checks and inits WBT
2. Using wbt_init_enable_default() in blk_register_queue() to ensure
proper initialization during queue registration
3. Move wbt_init() out of wbt_enable_default() which is only for enabling
disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the
original lock warning can be avoided.
4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling
code since it's no longer needed
This ensures WBT is properly initialized before any IO can be submitted,
preventing the counter from going negative.
Affected
18 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | linux | < linux 6.18.3-1 (forky) | linux 6.18.3-1 (forky) |
| linux | linux | — | — |
| linux | linux | >= 78c271344b6f64ce24c845e54903e09928cf2061 < f55201fb3becff6a903fd29f4d1147cc7e91eb0c | f55201fb3becff6a903fd29f4d1147cc7e91eb0c |
| linux | linux | >= 78c271344b6f64ce24c845e54903e09928cf2061 < 9869d3a6fed381f3b98404e26e1afc75d680cbf9 | 9869d3a6fed381f3b98404e26e1afc75d680cbf9 |
| linux | linux_kernel | >= 0 < 6.18.3-1 | 6.18.3-1 |
| linux | linux_kernel | >= 6.16.0 < 6.18.3 | 6.18.3 |
| ubuntu | linux-aws | — | — |
| ubuntu | linux-aws-6.17 | — | — |
| ubuntu | linux-azure | — | — |
| ubuntu | linux-azure-6.17 | — | — |
| ubuntu | linux-gcp | — | — |
| ubuntu | linux-gcp-6.17 | — | — |
| ubuntu | linux-hwe-6.17 | — | — |
| ubuntu | linux-oem-6.17 | — | — |
| ubuntu | linux-oracle | — | — |
| ubuntu | linux-oracle-6.17 | — | — |
| ubuntu | linux-raspi | — | — |
| ubuntu | linux-realtime-6.17 | — | — |
CVSS provenance
vendor_ubuntu6.4MEDIUM
vendor_redhat5.5LOW
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
VulDB
Linux Kernel up to 6.18.2/6.19-rc1 wbt_enable_default initialization (Nessus ID 307549 / WID-SEC-2026-0086)
vuldb·2026-04-21
CVE-2025-68807 [CRITICAL] Linux Kernel up to 6.18.2/6.19-rc1 wbt_enable_default initialization (Nessus ID 307549 / WID-SEC-2026-0086)
A vulnerability classified as critical was found in Linux Kernel up to 6.18.2/6.19-rc1. Affected by this vulnerability is the function wbt_enable_default. Executing a manipulation can lead to improper initialization.
This vulnerability appears as CVE-2025-68807. The attacker needs to be present on the local network. There is no available exploit.
Upgrading the affected component is advised.
GHSA
GHSA-89m4-pmw6-jxqj: In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_def
ghsa_unreviewed·2026-01-13
CVE-2025-68807 GHSA-89m4-pmw6-jxqj: In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_def
In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.
The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:
rq_wait[0]:
inflight: -1
has_waiters: True
rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter
will become negative.
And result
OSV
block: fix race between wbt_enable_default and IO submission
osv·2026-01-13
CVE-2025-68807 block: fix race between wbt_enable_default and IO submission
block: fix race between wbt_enable_default and IO submission
In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.
The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:
rq_wait[0]:
inflight: -1
has_waiters: True
rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_track()
OSV
CVE-2025-68807: In the Linux kernel, the following vulnerability has been resolved: block: fix race between wbt_enable_default and IO submission When wbt_enable_defau
osv·2026-01-13
CVE-2025-68807 CVE-2025-68807: In the Linux kernel, the following vulnerability has been resolved: block: fix race between wbt_enable_default and IO submission When wbt_enable_defau
In the Linux kernel, the following vulnerability has been resolved: block: fix race between wbt_enable_default and IO submission When wbt_enable_default() is moved out of queue freezing in elevator_change(), it can cause the wbt inflight counter to become negative (-1), leading to hung tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter is in an inconsistent state. The issue occurs because wbt_enable_default() could race with IO submission, allowing the counter to be decremented before proper initialization. This manifests as: rq_wait[0]: inflight: -1 has_waiters: True rwb_enabled() checks the state, which can be updated exactly between wbt_wait() (rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter will become negative. And results in h
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-05-07·CVSS 6.4
CVE-2025-71149 [MEDIUM] Linux kernel vulnerabilities
Title: Linux kernel 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- ACPI drivers;
-
Ubuntu
Linux kernel (Raspberry Pi) vulnerabilities
vendor_ubuntu·2026-05-07·CVSS 6.4
CVE-2025-68781 [MEDIUM] Linux kernel (Raspberry Pi) vulnerabilities
Title: Linux kernel (Raspberry Pi) 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
-
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-04-23·CVSS 6.4
CVE-2025-68801 [MEDIUM] Linux kernel vulnerabilities
Title: Linux kernel 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- ACPI drivers;
-
Ubuntu
Linux kernel (GCP) vulnerabilities
vendor_ubuntu·2026-04-17·CVSS 6.4
CVE-2025-68736 [MEDIUM] Linux kernel (GCP) vulnerabilities
Title: Linux kernel (GCP) 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- ACPI driv
Ubuntu
Linux kernel (Real-time) vulnerabilities
vendor_ubuntu·2026-04-17·CVSS 6.4
CVE-2025-68736 [MEDIUM] Linux kernel (Real-time) vulnerabilities
Title: Linux kernel (Real-time) 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- ACP
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-04-16·CVSS 6.4
CVE-2025-68736 [MEDIUM] Linux kernel vulnerabilities
Title: Linux kernel 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)
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:
- MIPS architecture;
- PowerPC architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer subsystem;
- Cryptographic API;
- ACPI drivers;
-
Red Hat
kernel: block: fix race between wbt_enable_default and IO submission
vendor_redhat·2026-01-13·CVSS 5.5
CVE-2025-68807 [LOW] CWE-909 kernel: block: fix race between wbt_enable_default and IO submission
kernel: block: fix race between wbt_enable_default and IO submission
In the Linux kernel, the following vulnerability has been resolved:
block: fix race between wbt_enable_default and IO submission
When wbt_enable_default() is moved out of queue freezing in elevator_change(),
it can cause the wbt inflight counter to become negative (-1), leading to hung
tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter
is in an inconsistent state.
The issue occurs because wbt_enable_default() could race with IO submission,
allowing the counter to be decremented before proper initialization. This manifests
as:
rq_wait[0]:
inflight: -1
has_waiters: True
rwb_enabled() checks the state, which can be updated exactly between wbt_wait()
(rq_qos_throttle()) and wbt_track()(rq_qos_trac
Debian
CVE-2025-68807: linux - In the Linux kernel, the following vulnerability has been resolved: block: fix ...
vendor_debian·2025
CVE-2025-68807 [LOW] CVE-2025-68807: linux - In the Linux kernel, the following vulnerability has been resolved: block: fix ...
In the Linux kernel, the following vulnerability has been resolved: block: fix race between wbt_enable_default and IO submission When wbt_enable_default() is moved out of queue freezing in elevator_change(), it can cause the wbt inflight counter to become negative (-1), leading to hung tasks in the writeback path. Tasks get stuck in wbt_wait() because the counter is in an inconsistent state. The issue occurs because wbt_enable_default() could race with IO submission, allowing the counter to be decremented before proper initialization. This manifests as: rq_wait[0]: inflight: -1 has_waiters: True rwb_enabled() checks the state, which can be updated exactly between wbt_wait() (rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter will become negative. And results in h
No detection rules found.
No public exploits indexed.
2026-01-13
Published