{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40158", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.176Z", "datePublished": "2025-11-12T10:23:29.516Z", "dateUpdated": "2026-08-05T12:08:08.096Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:08:08.096Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: use RCU in ip6_output()\n\nUse RCU in ip6_output() in order to use dst_dev_rcu() to prevent\npossible UAF.\n\nWe can remove rcu_read_lock()/rcu_read_unlock() pairs\nfrom ip6_finish_output2()." } ], "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_output()` is the IPv6 egress path for *forwarded* packets — `ip6_forward()` → `ip6_forward_finish()` → `dst_output()` → `ip6_output()` — so a remote, unauthenticated attacker's IPv6 traffic drives the vulnerable function on any Linux router, gateway, or container/cloud host, matching sibling CVE-2025-40168 in the same dst_dev_rcu series.\nAC:H - The remote attacker supplies the traffic side of the race freely, but the `dst_dev_put()` side (netdev unregister/link down, veth deletion, route-exception teardown) is an operational event they cannot influence from the network, and the freed `inet6_dev`/`net_device` must be reallocated with useful content to escalate beyond a crash.\nPR:N - Packets on the forwarding path reach `ip6_output()` with no credentials, no socket, and no local account on the target — the router transmits them automatically. (Even in the purely local framing the netns/CAP_NET_ADMIN half is obtainable via `unshare -Urn`, so no real privilege is required either way.)\nUI:N - Transmission and forwarding happen unconditionally in softirq/process context on packet arrival; no administrator or local user has to open, mount, or click anything.\nS:U - The freed `inet6_dev` and `net_device` are kernel objects and the corruption stays 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 `idev->cnf.disable_ipv6`, `idev->stats.ipv6`, `dev->hard_header_len`/`needed_headroom`, `dev->header_ops` and `dev->flags`; once the freed slab object is reallocated the attacker can steer header-expansion sizes and the egress device, yielding kernel memory disclosure and out-of-device packet leakage.\nI:H - `IP6_INC_STATS`/`IP6_UPD_PO_STATS` expand to `SNMP_INC_STATS64(idev->stats.ipv6, field)`, performing a 64-bit increment through a per-CPU pointer loaded from freed memory — an arbitrary-write primitive after reallocation — and `neigh_output()` → `dev_queue_xmit()` makes an indirect call through `dev->netdev_ops->ndo_start_xmit` read from the freed `net_device`, giving control-flow hijack.\nA:H - Dereferencing a freed `inet6_dev`/`net_device` on the packet transmit path reliably oopses or panics the kernel (KASAN slab-use-after-free), and the crash is in the core IPv6 output path so it takes down the whole forwarding 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": "0393f85c3241c19ba8550f04a812e7d19f6b3082", "status": "affected", "versionType": "git" }, { "version": "4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36", "lessThan": "11709573cc4e48dc34c80fc7ab9ce5b159e29695", "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": "6.17.3", "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": "6.17.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0393f85c3241c19ba8550f04a812e7d19f6b3082" }, { "url": "https://git.kernel.org/stable/c/11709573cc4e48dc34c80fc7ab9ce5b159e29695" } ], "title": "ipv6: use RCU in ip6_output()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-16T20:00:29.008533Z", "id": "CVE-2025-40158", "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": "2026-06-16T20:00:37.150Z" } } ] } }