{"id":"CVE-2026-53260","revision":null,"records":[{"revision":"be456bcc9ebf4ab0bf2238172bc023a1","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-53260","aliases":[],"title":"tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().\n\nsyzbot reported a weird reqsk->rsk_refcnt underflow in\n__inet_csk_reqsk_queue_drop().\n\nThe captured reqsk_put() in __inet_csk_reqsk_queue_drop()\nis called only when it successfully removes reqsk from ehash.\n\nMoreover, reqsk_timer_handler() calls another reqsk_put()\nafter that.\n\nThis indicates that the reqsk was missing both refcnts for\nehash and the timer itself.\n\nSince all the syzbot reports had PREEMPT_RT enabled, the only\npossible scenario is that reqsk_queue_hash_req() is preempted\nafter mod_timer() and before refcount_set(), and then the timer\ntriggered after 1s aborts the reqsk due to its listener's close().\n\nLet's wrap mod_timer() and refcount_set() with\npreempt_disable_nested() and preempt_enable_nested().\n\nNote that inet_ehash_insert() holds the normal spin_lock()\n(mutex in PREEMPT_RT), so it must be called outside of\npreempt_disable_nested(), but this is fine.\n\nThe lookup path just ignores 0 sk_refcnt entries in ehash\nand tries to create another reqsk, but this will fail at\ninet_ehash_insert().\n\n[0]:\nrefcount_t: underflow; use-after-free.\nWARNING: lib/refcount.c:28 at refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28, CPU#0: ktimers/0/16\nModules linked in:\nCPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}\nTainted: [L]=SOFTLOCKUP\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026\nRIP: 0010:refcount_warn_saturate+0xb2/0x110 lib/refcount.c:28\nCode: e4 7d d1 0a 67 48 0f b9 3a eb 4a e8 38 3d 23 fd 48 8d 3d e1 7d d1 0a 67 48 0f b9 3a eb 37 e8 25 3d 23 fd 48 8d 3d de 7d d1 0a <67> 48 0f b9 3a eb 24 e8 12 3d 23 fd 48 8d 3d db 7d d1 0a 67 48 0f\nRSP: 0000:ffffc90000157948 EFLAGS: 00010246\nRAX: ffffffff84a1301b RBX: 0000000000000003 RCX: ffff88801ca98000\nRDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffffff8f72ae00\nRBP: ffffffff99ae3b01 R08: ffff88801ca98000 R09: 0000000000000005\nR10: 0000000000000100 R11: 0000000000000004 R12: ffff8880425ef568\nR13: ffff8880425ef4f8 R14: ffff8880425ef578 R15: 0000000000000000\nFS: 0000000000000000(0000) GS:ffff888126386000(0000) knlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f7b46710e9c CR3: 000000000dbb6000 CR4: 00000000003526f0\nCall Trace:\n \n __refcount_sub_and_test include/linux/refcount.h:400 [inline]\n __refcount_dec_and_test include/linux/refcount.h:432 [inline]\n refcount_dec_and_test include/linux/refcount.h:450 [inline]\n reqsk_put include/net/request_sock.h:136 [inline]\n __inet_csk_reqsk_queue_drop+0x3ce/0x440 net/ipv4/inet_connection_sock.c:1007\n reqsk_timer_handler+0x651/0xdf0 net/ipv4/inet_connection_sock.c:1137\n call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748\n expire_timers kernel/time/timer.c:1799 [inline]\n __run_timers kernel/time/timer.c:2374 [inline]\n __run_timer_base+0x6a3/0x9f0 kernel/time/timer.c:2386\n run_timer_base kernel/time/timer.c:2395 [inline]\n run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403\n handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622\n __do_softirq kernel/softirq.c:656 [inline]\n run_ktimerd+0x69/0x100 kernel/softirq.c:1151\n smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160\n kthread+0x388/0x470 kernel/kthread.c:436\n ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n ","state":0,"publishedAt":"2026-06-25T08:39:49.229+00:00","modifiedAt":"2026-10-19T19:57:32.259+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ipv4/inet_connection_sock.c\"\n ],\n \"versions\": [\n {\n \"version\": \"d2d6422f8bd17c6bb205133e290625a564194496\",\n \"lessThan\": \"889fc99967007e2493833515a645cb2d800f6742\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d2d6422f8bd17c6bb205133e290625a564194496\",\n \"lessThan\": \"de5a46f3b2c8d3cd20afa158bd3a725e3e3d6fd3\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d2d6422f8bd17c6bb205133e290625a564194496\",\n \"lessThan\": \"b183215ff714efb747d9d5a429322ba6404b5401\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"d2d6422f8bd17c6bb205133e290625a564194496\",\n \"lessThan\": \"e10902df24488ca722303133acfc82490f7d59ad\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/ipv4/inet_connection_sock.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6.12\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.12\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.97\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.40\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0.13\",\n \"lessThanOrEqual\": \"7.0.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8,"severity":"CRITICAL"}],"references":["https://git.kernel.org/stable/c/889fc99967007e2493833515a645cb2d800f6742","https://git.kernel.org/stable/c/de5a46f3b2c8d3cd20afa158bd3a725e3e3d6fd3","https://git.kernel.org/stable/c/b183215ff714efb747d9d5a429322ba6404b5401","https://git.kernel.org/stable/c/e10902df24488ca722303133acfc82490f7d59ad"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-53260","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-53260","identifiers":["CVE-2026-53260"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-08T19:47:20.1649891+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-08T19:47:20.1649891+00:00","lastSuccessAt":"2026-11-08T19:47:20.3951142+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:20.3951146+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-3b79c659b4ac42b2801e63ff6ff3a882","complete":false,"records":13666,"lastAttemptAt":"2026-11-08T19:47:46.1695591+00:00","lastSuccessAt":"2026-11-08T19:47:46.166+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:46.166+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13206,"expectedIdentifiers":13706,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-08T19:47:20.0165357+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:20.0165357+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-fde804134ecdda0ddd5ff5c26ee1fff5a6fa659311f7ef2e51c6ad54964db0e2","complete":true,"records":1971,"lastAttemptAt":"2026-11-08T19:47:19.7560084+00:00","lastSuccessAt":"2026-11-06T19:03:17.0399903+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:19.7560084+00:00","snapshotPublishedAt":"2026-11-06T18:17:57+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-964c14035e6f0f6478b2870fad6a7ef9f6045876d4a12af2c2e514521e54b6af","complete":true,"records":3055,"lastAttemptAt":"2026-11-08T19:47:20.1181272+00:00","lastSuccessAt":"2026-11-08T11:07:12.1927025+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:20.1181272+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-f8647d7ba64b1ba0dfdc7130944766d5b36d5b77d18fff0c79e651a4cff3c2b9","complete":true,"records":231293,"lastAttemptAt":"2026-11-08T19:47:19.9161497+00:00","lastSuccessAt":"2026-11-08T11:06:56.2918717+00:00","error":null,"lastVerifiedAt":"2026-11-08T19:47:19.9161497+00:00","snapshotPublishedAt":"2026-11-08T11:02:50+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}