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 ]

CVSS: 7.8Highscored by the publisher (CNA)
Exploited in the wild: Not knownUnvetted proof-of-concept code on GitHub; not in CISA KEV
EPSS: 5.4%chance of exploitation in the next 30 daystop 8% of scored CVEsFIRST score of 11 Nov 2026
Fix: Fixed in < 2.6.39, >= 5.10.261 and <= 5.10.*, >= 5.15.212 and <= 5.15.*per the vendor; 6 more listed below
Published: 21 May 2026analysed here 12 Nov 2026

Do first. Upgrade to a fixed release: < 2.6.39, >= 5.10.261 and <= 5.10.*, >= 5.15.212 and <= 5.15.*, >= 6.1.175 and <= 6.1.* (and 5 more below).

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: local
Weakness: CWE-416 Use After Free
Can a WAF block it?: No. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Product	Affected versions	Vendor says fixed in
Linux	>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < f3fa3424bceb128d2be4b3745506b22844b87db7>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 838ce5cb5d93c3ab8b27e75bc6ad905a94b752fd>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < d8cce4773c2b23d819baf5abedc62f7b430e8745>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 8a1fc8d698ac5e5916e3082a0f74450d71f9611f>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 6d52dfcb2a5db86e346cf51f8fcf2071b8085166>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 3fb7394a837740770f0d6b4b30567e60786a63f2>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 88614876370aac8ad1050ad785a4c095ba17ac11>= 8161239a8bcce9ad6b537c04a1fa3b5c68bae693 and < 3bfdc63936dd4773109b7b8c280c0f3b5ae7d3492.6.39Vendor says fixed in: < 2.6.39, >= 5.10.261 and <= 5.10., >= 5.15.212 and <= 5.15., >= 6.1.175 and <= 6.1., >= 6.6.140 and <= 6.6., >= 6.12.86 and <= 6.12., >= 6.18.27 and <= 6.18., >= 7.0.4 and <= 7.0., >= 7.1 and <=	< 2.6.39>= 5.10.261 and <= 5.10.>= 5.15.212 and <= 5.15.>= 6.1.175 and <= 6.1.>= 6.6.140 and <= 6.6.>= 6.12.86 and <= 6.12.>= 6.18.27 and <= 6.18.>= 7.0.4 and <= 7.0.>= 7.1 and <=

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

Products named in our analysis

linux:linux_kernel

Fix and mitigation

WAF and other mitigations

Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.

Also consider: patch

Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Not listed as of our last sync.
Public exploit code: Unvetted proof-of-concept code on GitHub: 182 GitHub proofs of concept
CISA SSVC: exploitation poc, automatable no, technical impact totalAssessed by CISA 22 Aug 2026 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

GitHub proofs of concept

and 178 more repositories

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

21 May 2026Published
27 Jun 2026First proof-of-concept repository on GitHub (unvetted)36 days later
22 Aug 2026CISA SSVC assessment: exploitation poc56 days later
15 Oct 2026CVE record last updated54 days later
12 Nov 2026Analysed by vulneraibility.com28 days later

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Metric	Value	What it means
Attack vector	LocalLocal access required (shell, logged-in user).	Local access required (shell, logged-in user).
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	LowThe attacker needs basic user privileges.	The attacker needs basic user privileges.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2026-43499 being exploited?

Not confirmed. CVE-2026-43499 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 5.4% probability of exploitation in the next 30 days.

How severe is CVE-2026-43499?

CVE-2026-43499 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-43499?

Yes. A fix has been recorded for CVE-2026-43499. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-43499 affect?

CVE-2026-43499 affects linux:linux_kernel. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

12 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
PoC-in-GitHub: GitHub repositories that claim a proof of concept

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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