CVE-2026-63887
published 2026-07-19CVE-2026-63887: In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf…
PriorityP356critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EPSS
0.78%
54.1th percentile
In the Linux kernel, the following vulnerability has been resolved:
scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
iscsi_encode_text_output() concatenates "key=value\0" records into
login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer
allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call
sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check
the remaining buffer capacity:
*length += sprintf(output_buf, "%s=%s", er->key, er->value);
*length += 1;
output_buf = textbuf + *length;
The 8192-byte ceiling at iscsi_target_check_login_request() bounds the
*input* Login PDU payload, but a single PDU can carry up to 2048 minimal
four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte
"a=NotUnderstood\0" output record via iscsi_add_notunderstood_response().
2048 * 16 = 32 KiB of output into an 8 KiB buffer, producing a ~24 KiB
heap overrun in the kmalloc-8k slab.
The fix introduces a static iscsi_encode_text_record() helper that uses
snprintf() with a per-call bounds check against the remaining buffer,
and threads a u32 textbuf_size parameter through
iscsi_encode_text_output(). Both call sites in
iscsi_target_handle_csg_zero() (PHASE_SECURITY) and
iscsi_target_handle_csg_one() (PHASE_OPERATIONAL) pass
MAX_KEY_VALUE_PAIRS. On overflow the encoder logs the condition, calls
iscsi_release_extra_responses() to drop queued records, and returns -1;
both caller sites now emit ISCSI_STATUS_CLS_INITIATOR_ERR /
ISCSI_LOGIN_STATUS_INIT_ERR via iscsit_tx_login_rsp() before returning,
so the initiator sees an explicit failed-login response rather than a
silent connection drop. (Prior to this patch only the PHASE_OPERATIONAL
caller did that; the PHASE_SECURITY caller is converted to the same
shape.)
Affected
20 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < cb84e974fb172bc71386289f37b78ea679410b39 | cb84e974fb172bc71386289f37b78ea679410b39 |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < b19382dfc6e7dee6d3859ba44b6ca29e97a51627 | b19382dfc6e7dee6d3859ba44b6ca29e97a51627 |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < efe633e600a0ac68357206fede21b1ac8178f3b8 | efe633e600a0ac68357206fede21b1ac8178f3b8 |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < 4e9f0c4a645c995bc75c06c7b3644254ffb4c76b | 4e9f0c4a645c995bc75c06c7b3644254ffb4c76b |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < 30bf335e8fe170322080ee001f05ca29c50680b3 | 30bf335e8fe170322080ee001f05ca29c50680b3 |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < 594a40360012ce5f94c715d5e3b20fa3af7d525a | 594a40360012ce5f94c715d5e3b20fa3af7d525a |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < 26e4a304b7e6f1338c675d527608d32549c091db | 26e4a304b7e6f1338c675d527608d32549c091db |
| linux | linux | >= e48354ce078c079996f89d715dfa44814b4eba01 < bf33e01f88388c43e285492a63e539df6ffed64c | bf33e01f88388c43e285492a63e539df6ffed64c |
| linux | linux_kernel | — | — |
| ubuntu | linux-aws | — | — |
| ubuntu | linux-azure | — | — |
| ubuntu | linux-azure-fde | — | — |
| ubuntu | linux-gcp-7.0 | — | — |
| ubuntu | linux-ibm | — | — |
| ubuntu | linux-nvidia | — | — |
| ubuntu | linux-nvidia-7.0 | — | — |
| ubuntu | linux-nvidia-bos | — | — |
| ubuntu | linux-oracle | — | — |
| ubuntu | linux-raspi | — | — |
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vendor_redhat9.8CRITICAL
vendor_ubuntu9.1CRITICAL
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Ubuntu
Linux kernel (GCP) vulnerabilities
vendor_ubuntu·2026-09-07·CVSS 9.1
CVE-2026-52938 [CRITICAL] Linux kernel (GCP) vulnerabilities
Title: Linux kernel (GCP) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some Arm processors could complete a broadcast
translation lookaside buffer (TLB) invalidation before memory writes made
through the invalidated translation were globally observed. A local
attacker could possibly use this to write to memory after permission to do
so had been revoked, bypassing memory protections or escalating privileges.
(CVE-2025-10263)
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
Several security issues were disc
Ubuntu
Linux kernel (NVIDIA) vulnerabilities
vendor_ubuntu·2026-08-20·CVSS 7.0
CVE-2026-64234 [HIGH] Linux kernel (NVIDIA) vulnerabilities
Title: Linux kernel (NVIDIA) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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 platform drivers;
- Cryptographic API;
- PSP security protocol;
- ARM32 architecture;
- ARM64 architecture;
- MIPS architecture;
- PowerPC architecture;
- RISC-V architecture;
- S390 architecture;
- User-Mode Linux (UML);
- x
Ubuntu
Linux kernel (NVIDIA BaseOS) vulnerabilities
vendor_ubuntu·2026-08-20·CVSS 7.0
CVE-2026-64109 [HIGH] Linux kernel (NVIDIA BaseOS) vulnerabilities
Title: Linux kernel (NVIDIA BaseOS) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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 platform drivers;
- Cryptographic API;
- PSP security protocol;
- ARM32 architecture;
- ARM64 architecture;
- MIPS architecture;
- PowerPC architecture;
- RISC-V architecture;
- S390 architecture;
- User-Mode Linux (UM
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-07-28·CVSS 7.0
CVE-2026-64231 [HIGH] Linux kernel vulnerabilities
Title: Linux kernel vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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 platform drivers;
- Cryptographic API;
- PSP security protocol;
- ARM32 architecture;
- ARM64 architecture;
- MIPS architecture;
- PowerPC architecture;
- RISC-V architecture;
- S390 architecture;
- User-Mode Linux (UML);
- x86 archit
Ubuntu
Linux kernel (Azure) vulnerabilities
vendor_ubuntu·2026-07-24·CVSS 2.0
CVE-2026-64107 [LOW] Linux kernel (Azure) vulnerabilities
Title: Linux kernel (Azure) vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD processors did not properly clear data in
the floating point divider unit during speculative execution. A local
attacker could use this to expose sensitive information. (CVE-2025-54505)
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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 platfor
Ubuntu
Linux kernel vulnerabilities
vendor_ubuntu·2026-07-23·CVSS 7.0
CVE-2026-64107 [HIGH] Linux kernel vulnerabilities
Title: Linux kernel vulnerabilities
Summary: Several security issues were fixed in the Linux kernel.
It was discovered that some AMD Zen 2 processors did not properly isolate
shared resources in the operation cache. A local attacker could possibly
use this issue to corrupt instructions executed at a higher privilege
level, resulting in privilege escalation. (CVE-2025-54518)
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 platform drivers;
- PSP security protocol;
- ARM32 architecture;
- ARM64 architecture;
- MIPS architecture;
- PowerPC architecture;
- RISC-V architecture;
- S390 architecture;
- User-Mode Linux (UML);
- x86 architecture;
- Block layer
Red Hat
kernel: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
vendor_redhat·2026-07-19·CVSS 9.8
CVE-2026-63887 [CRITICAL] CWE-120 kernel: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
kernel: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
In the Linux kernel, the following vulnerability has been resolved:
scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
iscsi_encode_text_output() concatenates "key=value\0" records into
login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer
allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call
sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check
the remaining buffer capacity:
*length += sprintf(output_buf, "%s=%s", er->key, er->value);
*length += 1;
output_buf = textbuf + *length;
The 8192-byte ceiling at iscsi_target_check_login_request() bounds the
*input* Login PDU payload, but a single PDU can carry up to 2048 minimal
four-byte "a=b\0"
GHSA
In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf iscsi_encode_text_output() concatenates "key=value\0" rec
ghsa_unreviewed·2026-07-19
CVE-2026-63887 [CRITICAL] In the Linux kernel, the following vulnerability has been resolved: scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf iscsi_encode_text_output() concatenates "key=value\0" rec
In the Linux kernel, the following vulnerability has been resolved:
scsi: target: iscsi: Bound iscsi_encode_text_output() appends to rsp_buf
iscsi_encode_text_output() concatenates "key=value\0" records into
login->rsp_buf, an 8192-byte kzalloc(MAX_KEY_VALUE_PAIRS) buffer
allocated in iscsit_alloc_login_setup_buffer(). The three sprintf() call
sites in this function (lines 1398, 1411, 1424 in v7.1-rc2) never check
the remaining buffer capacity:
*length += sprintf(output_buf, "%s=%s", er->key, er->value);
*length += 1;
output_buf = textbuf + *length;
The 8192-byte ceiling at iscsi_target_check_login_request() bounds the
*input* Login PDU payload, but a single PDU can carry up to 2048 minimal
four-byte "a=b\0" pairs, each unknown key expanding to a 16-byte
"a=NotUnderstood\0" output reco
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/26e4a304b7e6f1338c675d527608d32549c091dbhttps://git.kernel.org/stable/c/30bf335e8fe170322080ee001f05ca29c50680b3https://git.kernel.org/stable/c/4e9f0c4a645c995bc75c06c7b3644254ffb4c76bhttps://git.kernel.org/stable/c/594a40360012ce5f94c715d5e3b20fa3af7d525ahttps://git.kernel.org/stable/c/b19382dfc6e7dee6d3859ba44b6ca29e97a51627https://git.kernel.org/stable/c/bf33e01f88388c43e285492a63e539df6ffed64chttps://git.kernel.org/stable/c/cb84e974fb172bc71386289f37b78ea679410b39https://git.kernel.org/stable/c/efe633e600a0ac68357206fede21b1ac8178f3b8
2026-07-19
Published