mpls: add seqcount to protect the platform_label{,s} pair
Affects Linux kernel MPLS code in 4.1.0 up to 6.6.160, 6.7.0 up to 6.12.114, and 6.13.0 up to 6.19.12. No vendor rating is given, and the facts list no fix.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 6.6.160, 6.12.114, 6.19.12
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: partial
Summary
In the Linux kernel, the following vulnerability has been resolved: mpls: add seqcount to protect the platform_label{,s} pair The RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have an inconsistent view of platform_labels vs platform_label in case of a concurrent resize (resize_platform_label_table, under platform_mutex). This can lead to OOB accesses. This patch adds a seqcount, so that we get a consistent snapshot. Note that mpls_label_ok is also susceptible to this, so the check against RTA_DST in rtm_to_route_config, done outside platform_mutex, is not sufficient. This value gets passed to mpls_label_ok once more in both mpls_route_add and mpls_route_del, so there is no issue, but that additional check must not be removed.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
4.1
- KernelLinux
From 4.1.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.19.12
References 5
Questions about CVE-2026-43042
What does this mean?
The MPLS platform label table can be resized while RCU-protected code is reading it. The reader can then see a platform_labels count that does not match the platform_label array, which causes out-of-bounds memory accesses.Source: git.kernel.org
Am I affected, and how do I check?
Kernels in the ranges 4.1.0 to before 6.6.160, 6.7.0 to before 6.12.114, and 6.13.0 to before 6.19.12. To check a system, compare the output of uname -r against these ranges. The bug needs a concurrent resize of the MPLS platform label table while RCU-protected code runs.Source: git.kernel.org
What should I do about it?
Move to a kernel at or past the fixed version for your branch: 6.6.160, 6.12.114, or 6.19.12.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data