CVE-2026-23456: Linux kernel · Out-of-bounds Read
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 8.2 High · fixed in fb6c3596823ec5dd09c2123340330d7448f51a59 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:30 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% 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 can reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fb6c3596823ec5dd09c2123340330d7448f51a59, c95dc674ebf01ecfb40388b6facfc89b81fed3b7, a2cd54b9348e485d338b3c132338a4410c99afaf +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Apr 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
|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
|
AI-suggested
This vulnerability has been fixed in multiple Linux kernel commits as listed in the established facts. Users and administrators should update their Linux kernel to a version that includes these fixes. There is no indication that additional mitigations are required beyond applying the official patches.
Description
A high-severity vulnerability (CVE-2026-23456) in the Linux kernel's netfilter nf_conntrack_h323 module allows an out-of-bounds read of 1-4 bytes due to improper boundary checking in the decode_int() function. This flaw occurs when processing malformed H.323/RAS packets, potentially causing a slab-out-of-bounds read. The issue has been fixed in specific Linux kernel commits.
References
- git.kernel.org/stable/c/a2cd54b9348e485d338b3c132338a4410c99afaf (opens in a new tab)
- git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7 (opens in a new tab)
- git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d (opens in a new tab)
- git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20 (opens in a new tab)
- git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2 (opens in a new tab)
- git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb (opens in a new tab)
- git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59 (opens in a new tab)
- git.kernel.org/stable/c/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a (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)