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CVE-2026-23121 Linux CVE debrief

A data-race vulnerability exists in the Linux kernel's mISDN component. The vulnerability is caused by a lack of proper synchronization when accessing the dev->work variable in the mISDN_read() and mISDN_poll() functions. This can lead to a data-race condition, which may result in undefined behavior. The issue arises from concurrent access to shared resources without adequate synchronization, potentially causing system instability. Developers should review the provided patches and update the Linux kernel to prevent exploitation.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-02-14
Original CVE updated
2026-10-19
Advisory published
2026-02-14
Advisory updated
2026-10-19

Who should care

Linux kernel developers and maintainers, as well as users of the Linux kernel who may be affected by this vulnerability. System administrators and security teams responsible for maintaining and securing Linux-based systems should also be aware of this issue and take necessary actions to prevent exploitation. Additionally, organizations relying on Linux kernel-based products or services should assess their exposure and apply patches or mitigations as needed

Why it matters

A data-race vulnerability exists in the Linux kernel's mISDN component, which may lead to undefined behavior and system instability.

  • Defenders should verify if their Linux kernel versions are affected and apply patches accordingly.
  • This vulnerability may lead to undefined behavior, which could result in system instability or crashes.
  • Defenders should monitor the system for potential issues related to the mISDN component.

Technical summary

The Linux kernel's mISDN component has a data-race vulnerability caused by a lack of proper synchronization when accessing the dev->work variable in the mISDN_read() and mISDN_poll() functions. This issue can lead to undefined behavior and system instability. The vulnerability is addressed by adding READ_ONCE()/WRITE_ONCE() annotations to ensure proper synchronization. Linux kernel developers and maintainers should review and apply the provided patches to fix this issue. The vulnerability highlights the importance of proper synchronization in preventing data-races and ensuring system stability.

Defensive priority

Medium

Recommended defensive actions

  • Review and apply the provided patches to address the data-race vulnerability
  • Ensure that the Linux kernel is updated to a version that includes the fix
  • Monitor the system for potential issues related to the mISDN component
  • Verify if the Linux kernel version used is affected and prioritize patching
  • Perform a thorough review of system logs to detect potential anomalies
  • Consider implementing compensating controls for exposed systems
  • Track the status of remediation efforts and retest remediated assets

Evidence notes

The vulnerability is caused by a lack of proper synchronization when accessing the dev->work variable in the mISDN_read() and mISDN_poll() functions. The Linux kernel maintainers have resolved this issue by adding READ_ONCE()/WRITE_ONCE() annotations.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-23121 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-23121

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-23121 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-23121

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • mISDN: annotate data-race around dev->work

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/23xxx/CVE-2026-23121.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/d5d99cb9e0839093cd53aa3b28176fce2f820ca0

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/13f3b3b87068898056db4c79ee67052fbde11d43

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/accc3f8266d2a49881dbcf78c459477f4efa0ff3

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/fc8ba17fd3337bd8b1913c30b95df0fee00d8fb7

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/aa6e33cd74ca4965f2bbcb025e0b672fb0168a69

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/7ac345a93af31358e18e9606eb7b354691bf6757

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/8175dbf174d487afab81e936a862a8d9b8a1ccb6

    Supplemental source

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.