ipv6: fix Route Information option length validation

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74598
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:32 UTC
Updated2026-08-22 16:16:32 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc 2f6f94eda12430fb41b24b44a71e2ea4e93561d7 git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc 7eac87396c44a312be457ef41d4c5687883be9a2 git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc 7309529f257ae18e72112ef9f614edfd6df229bb git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc 0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc ff3cb05289b8a4ef95fa7ea14c7d34818359edbb git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc 3b2231e358d26e3aec5d8040b1fb777af03c5f05 git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc da64ed1f346ba84df574d6469fa2e422b2511719 git Not specified
CNA Linux Linux affected 70ceb4f53929f73746be72f73707cd9f8753e2fc d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824 git Not specified
CNA Linux Linux affected 2.6.17 Not specified
CNA Linux Linux unaffected 2.6.17 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/0b9e02f3bd31c888f2ccdc0ca08e546d6abe9c4d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7309529f257ae18e72112ef9f614edfd6df229bb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/da64ed1f346ba84df574d6469fa2e422b2511719 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ff3cb05289b8a4ef95fa7ea14c7d34818359edbb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7eac87396c44a312be457ef41d4c5687883be9a2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3b2231e358d26e3aec5d8040b1fb777af03c5f05 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2f6f94eda12430fb41b24b44a71e2ea4e93561d7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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