{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2024-50154", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2024-50154", "idYear": 2024, "status": "PUBLISHED", "publishedAt": "2024-11-07T09:31:30.855Z", "updatedAt": "2026-08-05T11:42:07.102Z", "importedAt": "2026-10-24T01:57:20.494Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().\n\nMartin KaFai Lau reported use-after-free [0] in reqsk_timer_handler().\n\n \"\"\"\n We are seeing a use-after-free from a bpf prog attached to\n trace_tcp_retransmit_synack. The program passes the req->sk to the\n bpf_sk_storage_get_tracing kernel helper which does check for null\n before using it.\n \"\"\"\n\nThe commit 83fccfc3940c (\"inet: fix potential deadlock in\nreqsk_queue_unlink()\") added timer_pending() in reqsk_queue_unlink() not\nto call del_timer_sync() from reqsk_timer_handler(), but it introduced a\nsmall race window.\n\nBefore the timer is called, expire_timers() calls detach_timer(timer, true)\nto clear timer->entry.pprev and marks it as not pending.\n\nIf reqsk_queue_unlink() checks timer_pending() just after expire_timers()\ncalls detach_timer(), TCP will miss del_timer_sync(); the reqsk timer will\ncontinue running and send multiple SYN+ACKs until it expires.\n\nThe reported UAF could happen if req->sk is close()d earlier than the timer\nexpiration, which is 63s by default.\n\nThe scenario would be\n\n 1. inet_csk_complete_hashdance() calls inet_csk_reqsk_queue_drop(),\n but del_timer_sync() is missed\n\n 2. reqsk timer is executed and scheduled again\n\n 3. req->sk is accept()ed and reqsk_put() decrements rsk_refcnt, but\n reqsk timer still has another one, and inet_csk_accept() does not\n clear req->sk for non-TFO sockets\n\n 4. sk is close()d\n\n 5. reqsk timer is executed again, and BPF touches req->sk\n\nLet's not use timer_pending() by passing the caller context to\n__inet_csk_reqsk_queue_drop().\n\nNote that reqsk timer is pinned, so the issue does not happen in most\nuse cases. [1]\n\n[0]\nBUG: KFENCE: use-after-free read in bpf_sk_storage_get_tracing+0x2e/0x1b0\n\nUse-after-free read at 0x00000000a891fb3a (in kfence-#1):\nbpf_sk_storage_get_tracing+0x2e/0x1b0\nbpf_prog_5ea3e95db6da0438_tcp_retransmit_synack+0x1d20/0x1dda\nbpf_trace_run2+0x4c/0xc0\ntcp_rtx_synack+0xf9/0x100\nreqsk_timer_handler+0xda/0x3d0\nrun_timer_softirq+0x292/0x8a0\nirq_exit_rcu+0xf5/0x320\nsysvec_apic_timer_interrupt+0x6d/0x80\nasm_sysvec_apic_timer_interrupt+0x16/0x20\nintel_idle_irq+0x5a/0xa0\ncpuidle_enter_state+0x94/0x273\ncpu_startup_entry+0x15e/0x260\nstart_secondary+0x8a/0x90\nsecondary_startup_64_no_verify+0xfa/0xfb\n\nkfence-#1: 0x00000000a72cc7b6-0x00000000d97616d9, size=2376, cache=TCPv6\n\nallocated by task 0 on cpu 9 at 260507.901592s:\nsk_prot_alloc+0x35/0x140\nsk_clone_lock+0x1f/0x3f0\ninet_csk_clone_lock+0x15/0x160\ntcp_create_openreq_child+0x1f/0x410\ntcp_v6_syn_recv_sock+0x1da/0x700\ntcp_check_req+0x1fb/0x510\ntcp_v6_rcv+0x98b/0x1420\nipv6_list_rcv+0x2258/0x26e0\nnapi_complete_done+0x5b1/0x2990\nmlx5e_napi_poll+0x2ae/0x8d0\nnet_rx_action+0x13e/0x590\nirq_exit_rcu+0xf5/0x320\ncommon_interrupt+0x80/0x90\nasm_common_interrupt+0x22/0x40\ncpuidle_enter_state+0xfb/0x273\ncpu_startup_entry+0x15e/0x260\nstart_secondary+0x8a/0x90\nsecondary_startup_64_no_verify+0xfa/0xfb\n\nfreed by task 0 on cpu 9 at 260507.927527s:\nrcu_core_si+0x4ff/0xf10\nirq_exit_rcu+0xf5/0x320\nsysvec_apic_timer_interrupt+0x6d/0x80\nasm_sysvec_apic_timer_interrupt+0x16/0x20\ncpuidle_enter_state+0xfb/0x273\ncpu_startup_entry+0x15e/0x260\nstart_secondary+0x8a/0x90\nsecondary_startup_64_no_verify+0xfa/0xfb", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "106e457953315e476b3642ef24be25ed862aaba3" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "c964bf65f80a14288d767023a1b300b30f5b9cd0" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "8459d61fbf24967839a70235165673148c7c7f17" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "5071beb59ee416e8ab456ac8647a4dabcda823b1" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "997ae8da14f1639ce6fb66a063dab54031cd61b3" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "51e34db64f4e43c7b055ccf881b7f3e0c31bb26d" }, { "version": "83fccfc3940c4a2db90fd7e7079f5b465cd8c6af", "status": "affected", "versionType": "git", "lessThan": "e8c526f2bdf1845bedaf6a478816a3d06fa78b8f" }, { "version": "d3a1196bfc462943694623412d8e03aaf172bdc1", "status": "affected", "versionType": "git" }, { "version": "4.1.11", "status": "affected", "versionType": "semver", "lessThan": "4.2" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.2", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.2" }, { "version": "5.4.293", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.237", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.170", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.115", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.59", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.11.6", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.11.*" }, { "version": "6.12", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }