Linux Kernel up to 6.18.7 mISDN mISDN_read/mISDN_poll race condition

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4.9$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.18.7. This vulnerability affects the function mISDN_read/mISDN_poll of the component mISDN. Executing a manipulation can lead to race condition. This vulnerability is handled as CVE-2026-23121. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.18.7. This vulnerability affects the function mISDN_read/mISDN_poll of the component mISDN. The manipulation with an unknown input leads to a race condition vulnerability. The CWE definition for the vulnerability is CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: mISDN: annotate data-race around dev->work dev->work can re read locklessly in mISDN_read() and mISDN_poll(). Add READ_ONCE()/WRITE_ONCE() annotations. BUG: KCSAN: data-race in mISDN_ioctl / mISDN_read write to 0xffff88812d848280 of 4 bytes by task 10864 on cpu 1: misdn_add_timer drivers/isdn/mISDN/timerdev.c:175 [inline] mISDN_ioctl+0x2fb/0x550 drivers/isdn/mISDN/timerdev.c:233 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583 x64_sys_call+0x14b0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88812d848280 of 4 bytes by task 10857 on cpu 0: mISDN_read+0x1f2/0x470 drivers/isdn/mISDN/timerdev.c:112 do_loop_readv_writev fs/read_write.c:847 [inline] vfs_readv+0x3fb/0x690 fs/read_write.c:1020 do_readv+0xe7/0x210 fs/read_write.c:1080 __do_sys_readv fs/read_write.c:1165 [inline] __se_sys_readv fs/read_write.c:1162 [inline] __x64_sys_readv+0x45/0x50 fs/read_write.c:1162 x64_sys_call+0x2831/0x3000 arch/x86/include/generated/asm/syscalls_64.h:20 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000 -> 0x00000001

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-23121 since 01/13/2026. The exploitation appears to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 299169 (Linux Distros Unpatched Vulnerability : CVE-2026-23121), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.249, 5.15.199, 6.1.162, 6.6.122, 6.12.68 or 6.18.8 eliminates this vulnerability. Applying the patch d5d99cb9e0839093cd53aa3b28176fce2f820ca0/13f3b3b87068898056db4c79ee67052fbde11d43/accc3f8266d2a49881dbcf78c459477f4efa0ff3/fc8ba17fd3337bd8b1913c30b95df0fee00d8fb7/aa6e33cd74ca4965f2bbcb025e0b672fb0168a69/7ac345a93af31358e18e9606eb7b354691bf6757/8175dbf174d487afab81e936a862a8d9b8a1ccb6 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (299169) and CERT Bund (WID-SEC-2026-0421). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Google Cloud Platform
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel
  • IBM QRadar SIEM

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 4.6
VulDB Temp Score: 4.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 299169
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23121

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.249/5.15.199/6.1.162/6.6.122/6.12.68/6.18.8
Patch: d5d99cb9e0839093cd53aa3b28176fce2f820ca0/13f3b3b87068898056db4c79ee67052fbde11d43/accc3f8266d2a49881dbcf78c459477f4efa0ff3/fc8ba17fd3337bd8b1913c30b95df0fee00d8fb7/aa6e33cd74ca4965f2bbcb025e0b672fb0168a69/7ac345a93af31358e18e9606eb7b354691bf6757/8175dbf174d487afab81e936a862a8d9b8a1ccb6

Timelineinfo

01/13/2026 CVE reserved
02/14/2026 +32 days Advisory disclosed
02/14/2026 +0 days VulDB entry created
05/06/2026 +81 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23121 (🔒)
GCVE (CVE): GCVE-0-2026-23121
GCVE (VulDB): GCVE-100-346096
CERT Bund: WID-SEC-2026-0421 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 02/14/2026 19:08
Updated: 05/06/2026 08:08
Changes: 02/14/2026 19:08 (59), 02/17/2026 00:26 (2), 02/19/2026 06:32 (1), 03/19/2026 02:47 (11), 05/06/2026 08:08 (7)
Complete: 🔍
Cache ID: 216::103

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