{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53559","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-10-04T15:14:15.923Z","datePublished":"2025-10-04T15:17:03.497Z","dateUpdated":"2026-08-05T09:14:50.051Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T09:14:50.051Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nip_vti: fix potential slab-use-after-free in decode_session6\n\nWhen ip_vti device is set to the qdisc of the sfb type, the cb field\nof the sent skb may be modified during enqueuing. Then,\nslab-use-after-free may occur when ip_vti device sends IPv6 packets.\nAs commit f855691975bb (\"xfrm6: Fix the nexthdr offset in\n_decode_session6.\") showed, xfrm_decode_session was originally intended\nonly for the receive path. IP6CB(skb)->nhoff is not set during\ntransmission. Therefore, set the cb field in the skb to 0 before\nsending packets."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Triggering requires a locally configured ip_vti device with an sfb qdisc attached and packets routed out of it, all of which is set up and driven through local netlink/rtnetlink and a local socket. Although forwarded traffic from a remote peer would also hit vti_tunnel_xmit on a router so configured, the vulnerable state depends entirely on local device/qdisc configuration, so Local is the defensible vector.\nAC:L - The attacker creates every precondition: the vti device, the sfb qdisc, and its rehash_interval/warmup_time tunables that control when q->slot flips and hashes[1] is populated with a siphash value overlapping IP6CB->nhoff. Once slot==1 every transmitted IPv6 packet performs the wild nh[nhoff] read, making the trigger deterministic and repeatable.\nPR:L - Creating the vti tunnel and attaching the sfb qdisc requires CAP_NET_ADMIN, but ip_vti is fully network-namespace aware (register_pernet_device with a per-netns ip_vti0 fallback), so an unprivileged user obtains the needed capability with unshare -Urn. Per kernel scoring guidance, CAP_NET_ADMIN reachable through user namespaces is Low, not High.\nUI:N - The attacker performs the entire sequence — configure the device and qdisc, add a route, send an IPv6 packet — with no action by any other user or administrator.\nS:U - The out-of-bounds access occurs in kernel heap memory and its consequences remain within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - decode_session6() reads a byte from freed or adjacent slab memory at an offset up to 64KB beyond the network header — an unbounded use-after-free read rather than a small bounded one — and that value steers the protocol state machine and xfrm flow key, providing an oracle on kernel heap contents.\nI:H - The kernel's IPsec flow decode (flowi6_proto, ports, and the ensuing ip6_route_output/xfrm_lookup_route policy selection) is driven by data read out of freed heap memory, so a security-relevant kernel decision is made on corrupted state; consistent with treating slab-use-after-free as a high integrity impact.\nA:H - The wild read dereferences an address up to 65535 bytes past the skb data allocation, which faults on unmapped memory or memory holes and reliably produces a KASAN slab-use-after-free splat and kernel oops. The attacker can repeat it on every transmitted packet, so it is a sustained crash/DoS."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/ip_vti.c"],"versions":[{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"82fb41c5de243e7dfa90f32ca58e35adaff56c1d","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"7dfe23659f3677c08a60a0056cda2d91a79c15ca","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"d34c30442d5e53a33cde79ca163320dbe2432cbd","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"0b4d69539fdea138af2befe08893850c89248068","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"e1e04cc2ef2c0c0866c19f5627149a76c2baae32","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"2b05bf5dc437f7891dd409a3eaf5058459391c7a","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"78e397a43e1c47321a4679cc49a6c4530bf820b9","status":"affected","versionType":"git"},{"version":"f855691975bb06373a98711e4cfe2c224244b536","lessThan":"6018a266279b1a75143c7c0804dd08a5fc4c3e0b","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/ipv4/ip_vti.c"],"versions":[{"version":"3.19","status":"affected"},{"version":"0","lessThan":"3.19","status":"unaffected","versionType":"semver"},{"version":"4.14.324","lessThanOrEqual":"4.14.*","status":"unaffected","versionType":"semver"},{"version":"4.19.293","lessThanOrEqual":"4.19.*","status":"unaffected","versionType":"semver"},{"version":"5.4.255","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.192","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.128","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.47","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.4.12","lessThanOrEqual":"6.4.*","status":"unaffected","versionType":"semver"},{"version":"6.5","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":"3.19","versionEndExcluding":"4.14.324"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"4.19.293"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"5.4.255"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"5.10.192"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"5.15.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"6.1.47"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"6.4.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.19","versionEndExcluding":"6.5"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/82fb41c5de243e7dfa90f32ca58e35adaff56c1d"},{"url":"https://git.kernel.org/stable/c/7dfe23659f3677c08a60a0056cda2d91a79c15ca"},{"url":"https://git.kernel.org/stable/c/d34c30442d5e53a33cde79ca163320dbe2432cbd"},{"url":"https://git.kernel.org/stable/c/0b4d69539fdea138af2befe08893850c89248068"},{"url":"https://git.kernel.org/stable/c/e1e04cc2ef2c0c0866c19f5627149a76c2baae32"},{"url":"https://git.kernel.org/stable/c/2b05bf5dc437f7891dd409a3eaf5058459391c7a"},{"url":"https://git.kernel.org/stable/c/78e397a43e1c47321a4679cc49a6c4530bf820b9"},{"url":"https://git.kernel.org/stable/c/6018a266279b1a75143c7c0804dd08a5fc4c3e0b"}],"title":"ip_vti: fix potential slab-use-after-free in decode_session6","x_generator":{"engine":"bippy-1.2.0"}}}}