CVE-2026-74598ipv6: fix Route Information option length validation
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | 70ceb4f53929f73746be72f73707cd9f8753e2fc builds before 2f6f94eda12430fb41b24b44a71e2ea4e93561d7; 70ceb4f53929f73746be72f73707cd9f8753e2fc builds before 7eac87396c44a312be457ef41d4c5687883be9a2; from 70ceb4f53929f73746be72f73707cd9f8753e2fc before 7309529f257ae18e72112ef9f614edfd6df229bb; 70ceb4f53929f73746be72f73707cd9f8753e2fc builds before 0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d; from 70ceb4f53929f73746be72f73707cd9f8753e2fc before ff3cb05289b8a4ef95fa7ea14c7d34818359edbb; 70ceb4f53929f73746be72f73707cd9f8753e2fc builds before 3b2231e358d26e3aec5d8040b1fb777af03c5f05; from 70ceb4f53929f73746be72f73707cd9f8753e2fc before da64ed1f346ba84df574d6469fa2e422b2511719; from 70ceb4f53929f73746be72f73707cd9f8753e2fc before d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824 | CNA record |
References
- https://git.kernel.org/stable/c/2f6f94eda12430fb41b24b44a71e2ea4e93561d7
- https://git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2
- https://git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb
- https://git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d
- https://git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb
- https://git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05
- https://git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719
- https://git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.