{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-40135","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T07:20:57.170Z","datePublished":"2025-11-12T10:23:23.051Z","dateUpdated":"2026-08-05T12:08:00.413Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:08:00.413Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: use RCU in ip6_xmit()\n\nUse RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent\npossible UAF."}],"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_xmit()` is the locally-originated IPv6 output path for TCP and SCTP, and is driven directly by remote packets — `tcp_v6_send_synack()` on an incoming SYN and `tcp_v6_send_response()` for RST/challenge-ACK both call it before any authentication. Any internet-facing host with an IPv6 TCP listener (or that merely replies with RST) exposes the vulnerable function to unauthenticated remote traffic.\nAC:H - The attacker freely supplies the transmit side of the race by sending TCP/SCTP traffic, but the `dst_dev_put()` side (netdev unregister/link-down, veth teardown, route-exception/pcpu-route destruction) is an operational event they cannot influence from the network, and escalating past a crash requires the freed `net_device`/`inet6_dev` slab object to be reallocated with attacker-useful content. This matches sibling CVE-2025-40158 and CVE-2025-40168 in the same dst_dev_rcu series.\nPR:N - SYNACK and RST generation happen with no credentials, no established session, and no local account on the target — the kernel transmits automatically on packet arrival. Even under a purely local framing, both halves of the race (IPv6 traffic plus veth create/delete and route flush) are available to any unprivileged user via `unshare -Urn`, so no real privilege is required either way.\nUI:N - Packet transmission occurs unconditionally in softirq or backlog-drain context when traffic arrives; no administrator or local user has to open, mount, configure, or click anything.\nS:U - The freed `net_device` and `inet6_dev` are kernel-internal objects and the resulting corruption stays entirely within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free read of `dev->hard_header_len`/`needed_headroom` via `LL_RESERVED_SPACE()`, of `idev->stats.ipv6`, and of `out->name`/`out->ifindex` inside the `NF_HOOK(NF_INET_LOCAL_OUT)` traversal; once the freed slab object is reallocated the attacker can steer header-expansion sizing and the recorded egress device, yielding kernel memory disclosure and misdirected packet leakage.\nI:H - `IP6_INC_STATS(net, idev, ...)` expands to `SNMP_INC_STATS64(idev->stats.ipv6, field)`, performing a 64-bit increment through a per-CPU pointer loaded from freed memory — a write primitive after reallocation — and the stale `dev` propagates into `skb->dev` and the netfilter hook state, giving control over structures used for further dispatch.\nA:H - Dereferencing a freed `inet6_dev`/`net_device` on the IPv6 transmit path reliably produces a KASAN slab-use-after-free splat, oops, or panic, and because the fault is in the core TCP/SCTP egress path it takes down the entire host."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_output.c"],"versions":[{"version":"4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36","lessThan":"f0a54d00d2f36de40266f47c27989853e8588656","status":"affected","versionType":"git"},{"version":"4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36","lessThan":"f69fec6287565fdeb61f65e700a1184352306943","status":"affected","versionType":"git"},{"version":"4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36","lessThan":"bd0905e2122e3680968cd0741966983490bf2ed3","status":"affected","versionType":"git"},{"version":"4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36","lessThan":"f7f9e924f23684b4b23cd9f976cceab24a968e34","status":"affected","versionType":"git"},{"version":"4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36","lessThan":"9085e56501d93af9f2d7bd16f7fcfacdde47b99c","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/ip6_output.c"],"versions":[{"version":"4.13","status":"affected"},{"version":"0","lessThan":"4.13","status":"unaffected","versionType":"semver"},{"version":"6.1.167","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.130","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.78","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.17.3","lessThanOrEqual":"6.17.*","status":"unaffected","versionType":"semver"},{"version":"6.18","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":"4.13","versionEndExcluding":"6.1.167"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.13","versionEndExcluding":"6.6.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.13","versionEndExcluding":"6.12.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.13","versionEndExcluding":"6.17.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.13","versionEndExcluding":"6.18"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/f0a54d00d2f36de40266f47c27989853e8588656"},{"url":"https://git.kernel.org/stable/c/f69fec6287565fdeb61f65e700a1184352306943"},{"url":"https://git.kernel.org/stable/c/bd0905e2122e3680968cd0741966983490bf2ed3"},{"url":"https://git.kernel.org/stable/c/f7f9e924f23684b4b23cd9f976cceab24a968e34"},{"url":"https://git.kernel.org/stable/c/9085e56501d93af9f2d7bd16f7fcfacdde47b99c"}],"title":"ipv6: use RCU in ip6_xmit()","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-16T19:58:56.548938Z","id":"CVE-2025-40135","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-06-16T19:59:06.997Z"}},{"x_adpType":"supplier","providerMetadata":{"orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","shortName":"siemens-SADP","dateUpdated":"2026-07-14T12:43:22.637Z"},"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.6","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.5","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.6","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.5","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.6","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.5","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.6","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.5","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.6","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","versions":[{"status":"affected","version":"V3.1.5","lessThan":"*","versionType":"custom"}],"defaultStatus":"unknown"}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-082556.html"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-019113.html"}]}]}}