{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31657", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.129Z", "datePublished": "2026-04-24T14:45:08.867Z", "dateUpdated": "2026-08-05T12:24:10.743Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:24:10.743Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: hold claim backbone gateways by reference\n\nbatadv_bla_add_claim() can replace claim->backbone_gw and drop the old\ngateway's last reference while readers still follow the pointer.\n\nThe netlink claim dump path dereferences claim->backbone_gw->orig and\ntakes claim->backbone_gw->crc_lock without pinning the underlying\nbackbone gateway. batadv_bla_check_claim() still has the same naked\npointer access pattern.\n\nReuse batadv_bla_claim_get_backbone_gw() in both readers so they operate\non a stable gateway reference until the read-side work is complete.\nThis keeps the dump and claim-check paths aligned with the lifetime\nrules introduced for the other BLA claim readers." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable BLA claim state is reachable through received batman-adv mesh packets carrying claim and ARP/DAT traffic, not through a local-only syscall path. In a multi-hop batman-adv deployment, a remote mesh peer can drive the packet paths that update and read the claim.\nAC:L - Although this is a race, the attacker can control both sides by flooding claim ownership changes and packets that trigger the claim readers. No special memory layout or victim timing condition beyond attacker-induced concurrency is required.\nPR:N - The packet receive path has no authentication or privilege check for a peer already able to send batman-adv mesh traffic. The netlink dump path has a CAP_NET_ADMIN-in-netns gate, but the packet-triggered path does not require local privileges.\nUI:N - No user action is required once the affected batman-adv mesh interface and default BLA/DAT features are active. The attacker only needs to send crafted/concurrent network traffic.\nS:U - The impact is within the Linux kernel on the vulnerable host. It does not cross a separate hypervisor, guest/host, or hardware-enforced security authority boundary.\nC:H - This is a use-after-free of a kernel heap `batadv_bla_backbone_gw` object, with readers accessing fields after the object can be freed and reused. Such UAF conditions are defensibly treated as enabling high confidentiality impact.\nI:H - The stale object includes a spinlock and mutable state, so dereferencing and locking freed/reused memory can corrupt kernel heap state. A kernel UAF is also potentially exploitable for write/control-flow primitives.\nA:H - The stale pointer can lead to invalid dereferences or spinlock operations on freed memory, causing kernel oops, panic, or hang. Repeated network traffic can retrigger the condition." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/batman-adv/bridge_loop_avoidance.c" ], "versions": [ { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "5202f071b367ffbc8e279fc7a00db14f5e587f52", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "69d1ce9c72eca91203ffdb8d08bacd511100aec6", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "f4858832ddef2f39f21e30b7226bbcd3c4b2bc96", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "2f55b58b5a0bbed192d60c444a45a49cdf1b545f", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "7962b522222628596ca9ecc8722efc95367aadbd", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "4dee4c0688443aaf5bbec74aa203c851d1d53c35", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "1f2dc36c297d27733f1b380ea644cf15a361bd7b", "status": "affected", "versionType": "git" }, { "version": "23721387c409087fd3b97e274f34d3ddc0970b74", "lessThan": "82d8701b2c930d0e96b0dbc9115a218d791cb0d2", "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/batman-adv/bridge_loop_avoidance.c" ], "versions": [ { "version": "3.5", "status": "affected" }, { "version": "0", "lessThan": "3.5", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.258", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.169", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.135", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.82", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.23", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.13", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "3.5", "versionEndExcluding": "5.10.258" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "5.15.209" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.1.169" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.6.135" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.12.82" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.18.23" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "6.19.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.5", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5202f071b367ffbc8e279fc7a00db14f5e587f52" }, { "url": "https://git.kernel.org/stable/c/69d1ce9c72eca91203ffdb8d08bacd511100aec6" }, { "url": "https://git.kernel.org/stable/c/f4858832ddef2f39f21e30b7226bbcd3c4b2bc96" }, { "url": "https://git.kernel.org/stable/c/2f55b58b5a0bbed192d60c444a45a49cdf1b545f" }, { "url": "https://git.kernel.org/stable/c/7962b522222628596ca9ecc8722efc95367aadbd" }, { "url": "https://git.kernel.org/stable/c/4dee4c0688443aaf5bbec74aa203c851d1d53c35" }, { "url": "https://git.kernel.org/stable/c/1f2dc36c297d27733f1b380ea644cf15a361bd7b" }, { "url": "https://git.kernel.org/stable/c/82d8701b2c930d0e96b0dbc9115a218d791cb0d2" } ], "title": "batman-adv: hold claim backbone gateways by reference", "x_generator": { "engine": "bippy-1.2.0" } } } }