{"id":"CVE-2026-52919","state":"PUBLISHED","title":"batman-adv: fix tp_meter counter underflow during shutdown","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: fix tp_meter counter underflow during shutdown\n\nbatadv_tp_sender_shutdown() unconditionally decrements the \"sending\"\natomic counter. If multiple paths (e.g. timeout, user cancel, and\nnormal finish) call this function, the counter can underflow to -1.\n\nSince the sender logic treats any non-zero value as \"still sending\",\na negative value causes the sender kthread to loop indefinitely.\nThis leads to a use-after-free when the interface is removed while\nthe zombie thread is still active.\n\nFix this by using atomic_xchg() to ensure the counter only transitions\nfrom 1 to 0 once.\n\n[sven: added missing change in batadv_tp_send]","publishedAt":"2026-06-24T07:14:15.201Z","updatedAt":"2026-08-05T12:31:41.245Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"e75e2ab463b5b34df6b98f94d740aff327ce9f6b","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"abae88fa254f2981d39ac003a7b302528a22af64","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"c66d20a3ff095e3f000551d208ec2606616db15c","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"c1bac194733aabd731aafa6a01350c229e187dba","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"01cefc5923889e29dbb5f281c3d457714ceb9c00","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"90ae3eae06b7b8ab9f6250b9497c860915b4c17b","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"aeae11c5dad9cd0d50723890bdd866f8e6db2e7d","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"94f3b133168d1c49895e7cc6afbcf1cc0b354602","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/batman-adv/tp_meter.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.8","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/batman-adv/tp_meter.c"]}],"references":["https://git.kernel.org/stable/c/e75e2ab463b5b34df6b98f94d740aff327ce9f6b","https://git.kernel.org/stable/c/abae88fa254f2981d39ac003a7b302528a22af64","https://git.kernel.org/stable/c/c66d20a3ff095e3f000551d208ec2606616db15c","https://git.kernel.org/stable/c/c1bac194733aabd731aafa6a01350c229e187dba","https://git.kernel.org/stable/c/01cefc5923889e29dbb5f281c3d457714ceb9c00","https://git.kernel.org/stable/c/90ae3eae06b7b8ab9f6250b9497c860915b4c17b","https://git.kernel.org/stable/c/aeae11c5dad9cd0d50723890bdd866f8e6db2e7d","https://git.kernel.org/stable/c/94f3b133168d1c49895e7cc6afbcf1cc0b354602"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/52xxx/CVE-2026-52919.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52919","state":"PUBLISHED","datePublished":"2026-06-24T07:14:15.201Z","dateUpdated":"2026-08-05T12:31:41.245Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.367Z"},"containers":{"cna":{"title":"batman-adv: fix tp_meter counter underflow during shutdown","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: fix tp_meter counter underflow during shutdown\n\nbatadv_tp_sender_shutdown() unconditionally decrements the \"sending\"\natomic counter. If multiple paths (e.g. timeout, user cancel, and\nnormal finish) call this function, the counter can underflow to -1.\n\nSince the sender logic treats any non-zero value as \"still sending\",\na negative value causes the sender kthread to loop indefinitely.\nThis leads to a use-after-free when the interface is removed while\nthe zombie thread is still active.\n\nFix this by using atomic_xchg() to ensure the counter only transitions\nfrom 1 to 0 once.\n\n[sven: added missing change in batadv_tp_send]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"e75e2ab463b5b34df6b98f94d740aff327ce9f6b","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"abae88fa254f2981d39ac003a7b302528a22af64","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"c66d20a3ff095e3f000551d208ec2606616db15c","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"c1bac194733aabd731aafa6a01350c229e187dba","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"01cefc5923889e29dbb5f281c3d457714ceb9c00","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"90ae3eae06b7b8ab9f6250b9497c860915b4c17b","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"aeae11c5dad9cd0d50723890bdd866f8e6db2e7d","versionType":"git"},{"version":"33a3bb4a3345bb511f9c69c913da95d4693e2a4e","status":"affected","lessThan":"94f3b133168d1c49895e7cc6afbcf1cc0b354602","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/batman-adv/tp_meter.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.8","versionType":"semver"},{"version":"5.10.258","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.209","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.175","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.142","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/batman-adv/tp_meter.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/e75e2ab463b5b34df6b98f94d740aff327ce9f6b"},{"url":"https://git.kernel.org/stable/c/abae88fa254f2981d39ac003a7b302528a22af64"},{"url":"https://git.kernel.org/stable/c/c66d20a3ff095e3f000551d208ec2606616db15c"},{"url":"https://git.kernel.org/stable/c/c1bac194733aabd731aafa6a01350c229e187dba"},{"url":"https://git.kernel.org/stable/c/01cefc5923889e29dbb5f281c3d457714ceb9c00"},{"url":"https://git.kernel.org/stable/c/90ae3eae06b7b8ab9f6250b9497c860915b4c17b"},{"url":"https://git.kernel.org/stable/c/aeae11c5dad9cd0d50723890bdd866f8e6db2e7d"},{"url":"https://git.kernel.org/stable/c/94f3b133168d1c49895e7cc6afbcf1cc0b354602"}],"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 - The vulnerable sender shutdown path is reached through the batman-adv generic netlink tp_meter start/cancel operations and mesh-interface teardown, which are local kernel control interfaces rather than packets alone. Adjacent mesh packets can influence timing, but an attacker must be able to initiate or cancel the tp_meter session locally to reliably hit the underflow.\nAC:L - The underflow occurs when multiple attacker-controllable stop paths act on the same session, such as a short test/timeout plus cancel or teardown. Although timing is involved, the attacker controls the session lifetime and can repeat the race, so this is low complexity.\nPR:L - The tp_meter genl commands use GENL_UNS_ADMIN_PERM, requiring CAP_NET_ADMIN in the caller's user namespace. Because batman-adv is netns-aware and can be driven from user namespaces when available, this is low rather than high privilege.\nUI:N - A local attacker with the required namespace capability can create/start/cancel/tear down the tp_meter session without any separate victim action. No user needs to open a file, mount anything, or interact with attacker-controlled data.\nS:U - The bug corrupts/uses kernel networking subsystem state within the same kernel security authority. It is not a VM escape, IOMMU bypass, or cross-authority boundary violation.\nC:H - The fix commit states the negative sender counter leaves a zombie kthread active and leads to a use-after-free during interface removal. Per kernel scoring guidance, a kernel UAF is treated as potentially enabling high confidentiality impact.\nI:H - The resulting use-after-free is kernel memory corruption and can plausibly be shaped into write/control-flow primitives in the most severe reasonable scenario. Per guidance, kernel UAFs are scored as high integrity impact.\nA:H - At minimum, the negative counter can keep the sender kthread looping indefinitely and hang teardown; the documented UAF can also crash the kernel. This is high availability impact."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:31:41.245Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"5.10.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"5.15.209"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.1.175"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.6.142"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.8","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}