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PatchSiren cyber security CVE debrief

CVE-2026-99012 Linux CVE debrief

A use-after-free vulnerability exists in the Linux kernel's Bluetooth ISO connect function. This issue allows concurrent connect calls to interfere with each other, potentially leading to a use-after-free error when tearing down connections. The vulnerability arises from iso_sock_connect() checking the socket state before taking the socket lock and dropping the lock again before setting up a connection. Two callers can both pass the admission check while the socket is open or bound. Caller A can copy its destination for route selection, then caller B can replace the socket destination before A binds or connects the CIS. A then uses B's destination with the route selected for its A

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-23
Original CVE updated
2026-10-30
Advisory published
2026-10-23
Advisory updated
2026-10-30

Who should care

Defenders responsible for Linux kernel-based systems, particularly those using Bluetooth, should assess exposure and prioritize patching affected versions. This includes operators of Linux-based servers, desktops, and mobile devices that utilize Bluetooth functionality. Additionally, security teams and vulnerability management teams should be aware of the potential risks and take proactive measures to mitigate them.

Why it matters

Defenders should prioritize patching affected Linux kernel versions and monitoring Bluetooth connections for unusual activity due to a use-after-free vulnerability in the Bluetooth ISO connect function.

  • Potential use-after-free errors when tearing down connections
  • Unusual Bluetooth connection activity may indicate exploitation attempts
  • Patching affected versions can prevent potential exploitation

Technical summary

The Linux kernel's Bluetooth ISO connect function is vulnerable to a use-after-free error due to concurrent connect calls interfering with each other. This issue can lead to a use-after-free error when tearing down connections. The vulnerability arises from the lack of proper synchronization in the iso_sock_connect() function, allowing multiple callers to interfere with each other's operations. Defenders should prioritize patching affected Linux kernel versions and monitoring Bluetooth connections for unusual activity.

Defensive priority

Defenders should prioritize patching affected Linux kernel versions and monitoring Bluetooth connections for unusual activity.

Recommended defensive actions

  • Patch affected Linux kernel versions
  • Monitor Bluetooth connections for unusual activity
  • Implement additional logging and monitoring to detect potential exploitation attempts
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability was reported via KASAN and has been resolved in the Linux kernel. Multiple commits were referenced as part of the fix. The issue was identified through a combination of code review and testing, highlighting the need for defenders to prioritize patching affected Linux kernel versions. Evidence limits suggest that the vulnerability could be present in various Linux kernel versions, emphasizing the importance of verification and patching.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-99012 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-99012

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

  • CVE-2026-99012 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-99012

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

Supplemental references

  • Bluetooth: ISO: Serialize concurrent connect calls

    Unverified legacy reference

    URL: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/99xxx/CVE-2026-99012.json

    cve_program_cvelist_v5

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/a33de694226838d133dfdb7953c1955acb20df3d

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9b6ed57eb8c892ee7566b8c1bd06fdd0053b53de

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/1adcfe232c0f58890c2538211a841100ad0512bd

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c6489a3a0ac8c07f64cb5b44f005bc518f1048ac

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/3728f6b0d5990c0d500e929ba10baf93bee24f5e

    Supplemental source

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/e32d80293a0e1a160d5e5101daa8c82148c07510

    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.