net/sched: sch_netem: fix out-of-bounds access in packet corruption
Affects Linux kernel builds using netem packet corruption with fully non-linear AF_PACKET TX_RING packets over an IPIP tunnel. Fixed in 6.6.134, 6.12.81, 6.18.22 and 6.19.12 depending on branch.
- 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- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean?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 6.6.134, 6.12.81, 6.18.22, 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: total
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_netem: fix out-of-bounds access in packet corruption In netem_enqueue(), the packet corruption logic uses get_random_u32_below(skb_headlen(skb)) to select an index for modifying skb->data. When an AF_PACKET TX_RING sends fully non-linear packets over an IPIP tunnel, skb_headlen(skb) evaluates to 0. Passing 0 to get_random_u32_below() takes the variable-ceil slow path which returns an unconstrained 32-bit random integer. Using this unconstrained value as an offset into skb->data results in an out-of-bounds memory access. Fix this by verifying skb_headlen(skb) is non-zero before attempting to corrupt the linear data area. Fully non-linear packets will silently bypass the corruption logic.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
2.6.16
- KernelLinux
From 2.6.16 · fixed in 6.6.134; From 6.7.0 · fixed in 6.12.81; From 6.13.0 · fixed in 6.18.22; From 6.19.0 · fixed in 6.19.12
References 6
git.kernel.org
Questions about CVE-2026-31675
What does this mean?
The netem packet corruption code can pick a random offset into the packet data without a bounds check, so it can read or write memory outside the buffer. This is an out-of-bounds memory access inside the kernel.Source: git.kernel.org
Am I affected, and how do I check?
Kernels from 2.6.16 up to the fixed release for their branch are in the affected range: before 6.6.134, from 6.7.0 before 6.12.81, from 6.13.0 before 6.18.22, and from 6.19.0 before 6.19.12. Check the running version with uname -r. The bug needs netem packet corruption and fully non-linear packets sent through AF_PACKET TX_RING over an IPIP tunnel.Source: git.kernel.org
What should I do about it?
Upgrade to the fixed kernel for your branch: 6.6.134, 6.12.81, 6.18.22, or 6.19.12 or later.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