What’s Vulnerable › Vulnerabilities

CVE-2026-23083: fou: Don't allow 0 for FOU_ATTR_IPPROTO.

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-02-04 · updated 2026-10-19
• Weakness: CWE-20

Description

In the Linux kernel, the following vulnerability has been resolved: fou: Don't allow 0 for FOU_ATTR_IPPROTO. fou_udp_recv() has the same problem mentioned in the previous patch. If FOU_ATTR_IPPROTO is set to 0, skb is not freed by fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu(). Let's forbid 0 for FOU_ATTR_IPPROTO.

Affected products

• Linux kernel: from 3.18 before 5.10.249; from 5.11 before 5.15.199; from 5.16 before 6.1.162; from 6.2 before 6.6.122; from 6.7 before 6.12.68; from 6.13 before 6.18.8 — fixed in 5.10.249, 5.15.199, 6.1.162, 6.12.68, 6.18.8, 6.6.122

How to fix

Upgrade to a fixed version: Linux kernel 5.10.249, 5.15.199, 6.1.162, 6.12.68. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1cc98b8887cabb1808d2f4a37cd10a7be7574771
• https://git.kernel.org/stable/c/611ef4bd9c73d9e6d87bed57a635ff1fdd8c91ea
• https://git.kernel.org/stable/c/6e983789b7588ee59cbf303583546c043bad8e19
• https://git.kernel.org/stable/c/7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5
• https://git.kernel.org/stable/c/9b75dff8446ec871030d8daf5a69e74f5fe8b956
• https://git.kernel.org/stable/c/b7db31a52c3862a1a32202a273a4c32e7f5f4823
• https://git.kernel.org/stable/c/c7498f9bc390479ccfad7c7f2332237ff4945b03
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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