CVE-2026-23111: Linux kernel · netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in f41c5d151078c5348271ffaf8e7410d96f2d82f8 : patch Linux kernel soon.
Data as of 10 Nov 2026, 13:02 UTC
Sources agree
| CNA (Linux) | CVSS 3.1 | 7.8 |
|---|---|---|
| ADP (redhat-SADP) | CVSS 3.1 | 7.8 |
- 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
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-06-09.
- Patch
- Available – fixed in f41c5d151078c5348271ffaf8e7410d96f2d82f8, b9b6573421de51829f7ec1cce76d85f5f6fbbd7f, 1444ff890b4653add12f734ffeffc173d42862dd +9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 10 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
A fix is available in Linux kernel versions 5.15.200, 6.1.163, 6.4, 5.11, and others as listed in the fixedVersions. Users and administrators should upgrade to these fixed kernel versions to remediate the vulnerability. As a temporary mitigation, preventing the nf_tables kernel module from loading by blacklisting it can reduce exposure. Refer to vendor advisories such as Red Hat's for detailed instructions on patching and module blacklisting.
Description
A logic bug in the Linux kernel's nf_tables component causes an inverted element activity check during the abort path of a failed transaction. This flaw leads to a use-after-free condition where catchall verdict elements may reference a freed chain. Local unprivileged users can exploit this via user namespaces and nftables to cause denial of service or potentially escalate privileges. The issue affects multiple Linux kernel versions and has been fixed in later releases.
Reports on CVE-2026-23111
References
- git.kernel.org/stable/c/8c760ba4e36c750379d13569f23f5a6e185333f5 (opens in a new tab)
- git.kernel.org/stable/c/b9b6573421de51829f7ec1cce76d85f5f6fbbd7f (opens in a new tab)
- git.kernel.org/stable/c/42c574c1504aa089a0a142e4c13859327570473d (opens in a new tab)
- git.kernel.org/stable/c/1444ff890b4653add12f734ffeffc173d42862dd (opens in a new tab)
- git.kernel.org/stable/c/8b68a45f9722f2babe9e7bad00aa74638addf081 (opens in a new tab)
- git.kernel.org/stable/c/f41c5d151078c5348271ffaf8e7410d96f2d82f8 (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-253495.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)
- blog.exodusintel.com/2026/06/08/off-by-exploiting-a-use-after-free-in-the-linux-kernel/ (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-23111 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2439687 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23111.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:10996 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:18134 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:10108 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:9112 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:6570 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62639 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:62641 (opens in a new tab)