CVE-2026-80793

CVE CVE-2026-80793EUVD EUVD-2026-71436Published 2026-09-04T15:13:05.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: ipv4: reject undersized MTUs in ip_do_fragment() ip_do_fragment() subtracts the IPv4 header length from the effective MTU and passes the resulting payload MTU to ip_frag_next(). If the effective MTU is smaller than hlen + 8, ip_frag_next() rounds the fragment payload length down to zero. The fragmentation state then never makes forward progress: state->left, state->ptr and state->offset stay unchanged while ip_do_fragment() keeps allocating and transmitting header-only fragments until the softlockup detector fires. This is reproducible with a route installed using "mtu lock 20", but it is also reproducible without route MTU lock, for example by forwarding a packet to a device whose MTU is 20. Fix it in ip_do_fragment() by rejecting mtu < hlen + 8 with -EMSGSIZE, matching the existing IPv6 fragmentation check.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <515b6816ba0c12d8415c88e5f41e6ec029e35cfa; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a716a64a4ba68cd46f2745fba2b1099fe8e0aa59; patch: 7.3-rc1; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d9d1a676b033acabf8e5645f730486d1f8204a3f; patch: 0; patch: 6.18.47; 2.6.12; patch: 6.6.154; patch: 5.10.267; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3556beb8ca86677af2aca5bfbed6f8e790fccc83; patch: 6.12.106; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <74ce7389f8f562d39015f59a00ef7ad6acd37803; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c8a74adccaf028223054633b532593101dfcc581; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <36e0741833bd823866f8cb9f112f37cea1a70b60; patch: 6.1.185; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c0726f0caf8c6b3208552949e17d23634a2f3129; patch: 7.2.1; patch: 5.15.218; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b0ea911453ce7210e8200a07a94d2458bd1e6430; patch: 7.1.11

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

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Linux — Linux

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