CVE-2026-74598: Linux Vulnerability

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.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < 2f6f94eda12430fb41b24b44a71e2ea4e93561d7; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < 7eac87396c44a312be457ef41d4c5687883be9a2; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < 7309529f257ae18e72112ef9f614edfd6df229bb; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < 0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < ff3cb05289b8a4ef95fa7ea14c7d34818359edbb; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < 3b2231e358d26e3aec5d8040b1fb777af03c5f05; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < da64ed1f346ba84df574d6469fa2e422b2511719; >= 70ceb4f53929f73746be72f73707cd9f8753e2fc, < d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824
Linux	Linux	2.6.17

References

Timeline

Published: Aug 22, 2026
Last Modified: Aug 22, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-74598?

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.

How severe is CVE-2026-74598?

Severity scoring for CVE-2026-74598 is pending analysis.

How do I fix CVE-2026-74598?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

View all 2026CVEs →