How severe is CVE-2026-23121?

CVE-2026-23121 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-23121 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-23121?

CVE-2026-23121 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-23121?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-23121 have an EU (EUVD) identifier?

Yes. CVE-2026-23121 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5915.

When was CVE-2026-23121 published?

CVE-2026-23121 was published on 2026-02-14 and last updated on 2026-06-17.

CVE-2026-23121

CVE-2026-23121 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (2nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5915
Affected product: Linux Linux Kernel
Published: 2026-02-14
Last modified: 2026-06-17

Description

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

Frequently asked questions

What is CVE-2026-23121?: 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
How severe is CVE-2026-23121?: CVE-2026-23121 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-23121 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (2nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-23121?: CVE-2026-23121 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-23121?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-23121 have an EU (EUVD) identifier?: Yes. CVE-2026-23121 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5915.
When was CVE-2026-23121 published?: CVE-2026-23121 was published on 2026-02-14 and last updated on 2026-06-17.

References

Affected products (7)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.19:rc6:*:*:*:*:*:*

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