{ "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" } } } }