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Public proof of conceptFix available

CVE-2026-43499

A public proof of concept exists; no exploitation attested.

  • Published2026-05-21
  • Fixed in7.0.4 · 6.18.27 · 6.12.86 · 6.6.140 · 6.1.175 · 5.15.212
  • WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In the Linux kernel, the following vulnerability has been resolved: rtmutex: Use waiter::task instead of current in remove_waiter() remove_waiter() is used by the slowlock paths, but it is also used for proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from futex_requeue(). In the latter case waiter::task is not current, but remove_waiter() operates on current for the dequeue operation. That results in several problems: 1) the rbtree dequeue happens without waiter::task::pi_lock being held 2) the waiter task's pi_blocked_on state is not cleared, which leaves a dangling pointer primed for UAF around. 3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter task Use waiter::task instead of current in all related operations in remove_waiter() to cure those problems. [ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the changelog ]

Timeline

dates in UTC
  1. 2026-05-2113:16CVE publishedNVD

Versions per branch

NVD · OSV
Linux linux kernel
BranchAffectedFixed in
7.0≥ 6.19, < 7.0.47.0.4
7.0≥ 6.19.0, < 7.0.47.0.4
6.x≥ 6.13, < 6.18.276.18.27
6.x≥ 6.13.0, < 6.18.276.18.27
6.x≥ 6.7, < 6.12.866.12.86
6.x≥ 6.7.0, < 6.12.866.12.86
6.x≥ 6.2, < 6.6.1406.6.140
6.x≥ 6.2.0, < 6.6.1406.6.140
6.1≥ 2.6.39, < 6.1.1756.1.175
6.1≥ 5.16.0, < 6.1.1756.1.175
5.x≥ 5.11.0, < 5.15.2125.15.212
5.10≥ 2.6.39, < 5.10.2615.10.261

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA2 products

As Linux, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Linuxother versions: not affected

    https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    Affected
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < f3fa3424bceb128d2be4b3745506b22844b87db7fixed in f3fa3424bceb128d2be4b3745506b22844b87db7git
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fdfixed in 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fdgit
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < d8cce4773c2b23d819baf5abedc62f7b430e8745fixed in d8cce4773c2b23d819baf5abedc62f7b430e8745git
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 8a1fc8d698ac5e5916e3082a0f74450d71f9611ffixed in 8a1fc8d698ac5e5916e3082a0f74450d71f9611fgit
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 6d52dfcb2a5db86e346cf51f8fcf2071b8085166fixed in 6d52dfcb2a5db86e346cf51f8fcf2071b8085166git
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 3fb7394a837740770f0d6b4b30567e60786a63f2fixed in 3fb7394a837740770f0d6b4b30567e60786a63f2git
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 88614876370aac8ad1050ad785a4c095ba17ac11fixed in 88614876370aac8ad1050ad785a4c095ba17ac11git
    • ≥ 8161239a8bcce9ad6b537c04a1fa3b5c68bae693, < 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349fixed in 3bfdc63936dd4773109b7b8c280c0f3b5ae7d349git
  • Linuxother versions: affected

    https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    Affected
    • = 2.6.39no fix stated

    Not affected < 2.6.39 · ≥ 5.10.261, ≤ 5.10.* · ≥ 5.15.212, ≤ 5.15.* · ≥ 6.1.175, ≤ 6.1.* · ≥ 6.6.140, ≤ 6.6.* · ≥ 6.12.86, ≤ 6.12.* · ≥ 6.18.27, ≤ 6.18.*

    2 more version lines in the CVE record.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-05

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • bpftoolTuxCare:AlmaLinux:9.2all versions · fixed in 7.0.0-284.1101.el9_2.tuxcare.11.els8
  • kernelTuxCare:RHEL:7all versions · fixed in 3.10.0-1160.144.1.el7.tuxcare.els9and 10 other packages
  • kernelTuxCare:OracleLinux:7all versions · fixed in 3.10.0-1160.144.1.el7.tuxcare.els9and 10 other packages
  • kernelTuxCare:OracleLinux:6all versions · fixed in 2.6.32-754.35.8.el6.tuxcare.els33and 9 other packages
  • kernelTuxCare:CentOS:8.5all versions · fixed in 4.18.0-348.7.1.el8_5.tuxcare.els44and 21 other packages
  • kernelTuxCare:CentOS:8.4all versions · fixed in 4.18.0-305.25.1.el8_4.tuxcare.els44and 21 other packages
  • kernelTuxCare:CentOS:7all versions · fixed in 3.10.0-1160.144.1.el7.tuxcare.els9and 10 other packages
  • kernelTuxCare:CentOS:6all versions · fixed in 2.6.32-754.35.8.el6.tuxcare.els33and 9 other packages

108 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-43499 Red Hat Product Security2,429 products fixed · 22 known affected

    kernel: rtmutex: Use waiter::task instead of current in remove_waiter()

    kernel-rt as a component of Red Hat Enterprise Linux 9 · kernel-rt-core as a component of Red Hat Enterprise Linux 9 · kernel-rt-debug as a component of Red Hat Enterprise Linux 9 · +19 more

  • ICSA-26-295-11 CISA5 known affected

    Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.7 · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.7 · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.7 · +2 more

  • ICSA-26-295-16 CISA1 known affected

    Siemens SIMATIC S7-1500 TM MFP

    SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

  • SSA-457936 Siemens ProductCERT5 known affected

    SSA-457936: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.7

    SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= V3.1.7 · SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= V3.1.7 · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= V3.1.7 · +2 more

  • SSA-784472 Siemens ProductCERT1 known affected

    SSA-784472: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1

    SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

  • RHSA-2026:73187 Red Hat Product Security53 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

24 more advisories

Full record on NVD

Fix

  1. Update Linux linux kernel to 7.0.4 · 6.18.27 · 6.12.86 · 6.6.140 · 6.1.175 · 5.15.212 · 5.10.261
  2. Vendor fix Red Hat Product Security RHSA-2026:73187 · 53 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 The system must be rebooted for this update to take effect.
  3. Vendor fix Red Hat Product Security RHSA-2026:59146 · 35 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  4. Workaround from the vendor Red Hat Product Security RHSA-2026:73187 · 53 productsSee the security bulletin for a detailed mitigation procedure.
  5. Mitigation from the vendor CISA ICSA-26-295-16 · 1 productLimit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
  6. Mitigation from the vendor CISA ICSA-26-295-16 · 1 productOnly build and run applications from trusted sources.
  7. Mitigation from the vendor Siemens ProductCERT SSA-457936 · 5 productsLimit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2026-05-21
Last Modified
2026-10-15
NVD status
Modified
MSRC Title
rtmutex: Use waiter::task instead of current in remove_waiter()
GitHub Advisory
GHSA-cqc6-9f34-295v

Frequently asked questions

What is CVE-2026-43499?

In the Linux kernel, the following vulnerability has been resolved: rtmutex: Use waiter::task instead of current in remove_waiter() remove_waiter() is used by the slowlock paths, but it is also used for proxy-lock rollback in rt_mutex_start_proxy_lock() when invoked from futex_requeue(). In the latter case waiter::task is not current, but remove_waiter() operates on current for the dequeue operation. That results in several problems: 1) the rbtree dequeue happens without waiter::task::pi_lock being held 2) the waiter task's pi_blocked_on state is not cleared, which leaves a dangling pointer primed for UAF around. 3) rt_mutex_adjust_prio_chain() operates on the wrong top priority waiter task Use waiter::task instead of current in all related operations in remove_waiter() to cure those problems. [ tglx: Fixup rt_mutex_adjust_prio_chain(), add a comment and amend the changelog ]

Is CVE-2026-43499 actively exploited?

A proof-of-concept exploit exists for CVE-2026-43499, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-43499?

CVE-2026-43499 has a CVSS v3 base score of 7.8 (HIGH severity), with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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