{"cve":"CVE-2026-74598","nvd":{"published":"2026-08-22T16:16:32.170","modified":"2026-10-16T20:17:45.253","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix Route Information option length validation\n\nrt6_route_rcv() validates the Route Information option (RFC 4191) length\nagainst the prefix length, but both checks are off by one.\n\nrinfo->length is the ND option length in units of 8 octets and it\n*includes* the 8-byte option header, so an option carrying N bytes of\nprefix has length == 1 + N/8.  RFC 4191 section 2.3 requires length 3\nwhen Prefix Length is greater than 64, and 2 or 3 when it is greater\nthan 0.  The code accepts length >= 2 and length >= 1 respectively.\n\nipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix,\nso a Router Advertisement with (prefix_len=128, length=2) or\n(prefix_len=64, length=1) makes the kernel read up to 8 bytes past the\nend of the option.  Those bytes end up in the prefix of the route that\ngets installed, so they are visible to userspace:\n\n  # RA with a Route Information option (prefix_len=128, length=2)\n  # followed by a source link-layer address option, 01 01 de ad be ef ca fe\n  $ ip -6 route show\n  2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra\n                     ^^^^^^^^^^^^^^^^^^ the next option, read out of bounds\n\nWhen the Route Information option is the last one in the packet, those\neight bytes come from the skb tail room instead.\n\nReject the option lengths RFC 4191 does not allow.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","score":7.5},"cwes":[],"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"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:38.260478770+00:00"},"epss":{"cve":"CVE-2026-74598","score":0.00425,"percentile":0.36491,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}