CVE-2026-74598
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: fix Route Information option length validation rt6_route_rcv() validates the Route Information option (RFC 4191) length against the prefix length, but both checks are off by one. rinfo->length is the ND option length in units of 8 octets and it *includes* the 8-byte option header, so an option carrying N bytes of prefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3 when Prefix Length is greater than 64, and 2 or 3 when it is greater than 0. The code accepts length >= 2 and length >= 1 respectively. ipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix, so a Router Advertisement with (prefix_len=128, length=2) or (prefix_len=64, length=1) makes the kernel read up to 8 bytes past the end of the option. Those bytes end up in the prefix of the route that gets installed, so they are visible to userspace: # RA with a Route Information option (prefix_len=128, length=2) # followed by a source link-layer address option, 01 01 de ad be ef ca fe $ ip -6 route show 2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra ^^^^^^^^^^^^^^^^^^ the next option, read out of bounds When the Route Information option is the last one in the packet, those eight bytes come from the skb tail room instead. Reject the option lengths RFC 4191 does not allow.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d
- https://git.kernel.org/stable/c/2f6f94eda12430fb41b24b44a71e2ea4e93561d7
- https://git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05
- https://git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb
- https://git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2
- https://git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824
- https://git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719
- https://git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.