{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21765","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-12-29T08:45:45.761Z","datePublished":"2025-02-27T02:18:16.078Z","dateUpdated":"2026-08-05T11:54:18.497Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:54:18.497Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: use RCU protection in ip6_default_advmss()\n\nip6_default_advmss() needs rcu protection to make\nsure the net structure it reads does not disappear."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - `ip6_default_advmss()` is reached from the inbound IPv6 TCP handshake — `tcp_v6_rcv()` → `tcp_conn_request()` → `tcp_openreq_init_rwin()` and `tcp_v6_send_synack()` → `tcp_make_synack()` — so an unauthenticated remote peer sending a TCP SYN to any listening IPv6 socket executes the vulnerable read. No local access is needed.\nAC:H - The use-after-free only materialises if the `struct net` obtained from `dev_net(dst->dev)` is concurrently torn down (netns dismantle or `dev_change_net_namespace()`), a condition a remote attacker cannot influence, and the unprotected window between the pointer load and the `ip6_rt_min_advmss` dereference is narrow.\nPR:N - There is no privilege, capability or authentication check anywhere on the path; the code runs in softirq during SYN processing before any connection is established or credentials exchanged.\nUI:N - The attacker triggers the path entirely by transmitting packets to a listening IPv6 port; no action by a local user or victim process is required.\nS:U - The stale `struct net` dereference is confined to the kernel's own networking stack on the same host, crossing no virtualization, IOMMU or other security-authority boundary.\nC:H - This is a use-after-free read of a freed `net_cachep` slab object, and the recovered value directly influences the MSS advertised in the SYN-ACK, exposing reallocated kernel heap contents to the remote peer as an oracle.\nI:H - Reuse of a freed `struct net` means kernel state is derived from attacker-groomable reallocated slab memory; per UAF scoring guidance such object reuse is treated as corruption exploitable for further modification of kernel state.\nA:H - Dereferencing a `struct net` that has already been returned to the slab allocator can fault or read garbage, producing a KASAN splat, oops or panic in the TCP receive softirq path, and the trigger is repeatable with ordinary inbound connections."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"],"versions":[{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"78ad057472d8c76e0602402269222f9f9c698790","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"d02f30d220ef9511568a48dba8a9004c65f8d904","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"28de355b63ad42309ed5a03ee7c436c90512265b","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"84212387caadb211cd9dadd6fd5563bd37dc1f5e","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"4176a68b0db8fc74ac14fcd00ba8231371051dc2","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"713a40c892f40300d63691d9f85b2a23b48fe1e8","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"550ed693f47370502a71b85382e7f9e6417300b8","status":"affected","versionType":"git"},{"version":"5578689a4e3c04f2d43ea39736fd3fa396d80c6e","lessThan":"3c8ffcd248da34fc41e52a46e51505900115fc2a","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/route.c"],"versions":[{"version":"2.6.26","status":"affected"},{"version":"0","lessThan":"2.6.26","status":"unaffected","versionType":"semver"},{"version":"5.4.291","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.235","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.179","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.129","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.79","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.16","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.13.4","lessThanOrEqual":"6.13.*","status":"unaffected","versionType":"semver"},{"version":"6.14","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"5.4.291"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"5.10.235"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"5.15.179"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.1.129"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.6.79"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.12.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.13.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.26","versionEndExcluding":"6.14"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/78ad057472d8c76e0602402269222f9f9c698790"},{"url":"https://git.kernel.org/stable/c/d02f30d220ef9511568a48dba8a9004c65f8d904"},{"url":"https://git.kernel.org/stable/c/28de355b63ad42309ed5a03ee7c436c90512265b"},{"url":"https://git.kernel.org/stable/c/84212387caadb211cd9dadd6fd5563bd37dc1f5e"},{"url":"https://git.kernel.org/stable/c/4176a68b0db8fc74ac14fcd00ba8231371051dc2"},{"url":"https://git.kernel.org/stable/c/713a40c892f40300d63691d9f85b2a23b48fe1e8"},{"url":"https://git.kernel.org/stable/c/550ed693f47370502a71b85382e7f9e6417300b8"},{"url":"https://git.kernel.org/stable/c/3c8ffcd248da34fc41e52a46e51505900115fc2a"}],"title":"ipv6: 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