CVE-2026-23204: Linux kernel · net/sched: cls_u32: use skb_header_pointer_careful()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in e41a23e61259f5526af875c3b86b3d42a9bae0e5 : patch Linux kernel soon.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-06-16.
- Patch
- Available – fixed in e41a23e61259f5526af875c3b86b3d42a9bae0e5, cfa745830e45ecb75c061aa34330ee0cac941cc7, cabd1a976375780dabab888784e356f574bbaed8 +4
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 14 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_u32: use skb_header_pointer_careful() skb_header_pointer() does not fully validate negative @offset values. Use skb_header_pointer_careful() instead. GangMin Kim provided a report and a repro fooling u32_classify(): BUG: KASAN: slab-out-of-bounds in u32_classify+0x1180/0x11b0 net/sched/cls_u32.c:221
References
- git.kernel.org/stable/c/66e4b63d61c15de6ca5332d9ca6db59a404d7136 (opens in a new tab)
- git.kernel.org/stable/c/29681ed51e737be14d18ecd1c304c57002e4b72c (opens in a new tab)
- git.kernel.org/stable/c/cfa745830e45ecb75c061aa34330ee0cac941cc7 (opens in a new tab)
- git.kernel.org/stable/c/13336a6239b9d7c6e61483017bb8bdfe3ceb10a5 (opens in a new tab)
- git.kernel.org/stable/c/e41a23e61259f5526af875c3b86b3d42a9bae0e5 (opens in a new tab)
- git.kernel.org/stable/c/8a672f177ebe19c93d795fbe967846084fbc7943 (opens in a new tab)
- git.kernel.org/stable/c/cabd1a976375780dabab888784e356f574bbaed8 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)