CVE Catalog

CVE-2026-74598

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.43%

35th percentile - higher than 35% of all known CVEs

Summary

In the Linux kernel, the rt6_route_rcv() function has an incorrect validation of the Route Information option length (RFC 4191). Due to an off-by-one error, the kernel can read up to 8 bytes past the end of the option, potentially leaking data from adjacent memory into routes visible to userspace.

Risk Assessment

An attacker on the local network can send a crafted Router Advertisement, causing kernel memory disclosure to userspace, potentially revealing sensitive information.

Recommendation

Apply the kernel update that rejects disallowed Route Information option lengths.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS