{ "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-2025-40186", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-40186", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-11-12T21:56:29.033Z", "updatedAt": "2026-10-15T22:02:39.982Z", "importedAt": "2026-10-24T01:57:34.152Z", "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: Don't call reqsk_fastopen_remove() in tcp_conn_request().", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: Don't call reqsk_fastopen_remove() in tcp_conn_request().\n\nsyzbot reported the splat below in tcp_conn_request(). [0]\n\nIf a listener is close()d while a TFO socket is being processed in\ntcp_conn_request(), inet_csk_reqsk_queue_add() does not set reqsk->sk\nand calls inet_child_forget(), which calls tcp_disconnect() for the\nTFO socket.\n\nAfter the cited commit, tcp_disconnect() calls reqsk_fastopen_remove(),\nwhere reqsk_put() is called due to !reqsk->sk.\n\nThen, reqsk_fastopen_remove() in tcp_conn_request() decrements the\nlast req->rsk_refcnt and frees reqsk, and __reqsk_free() at the\ndrop_and_free label causes the refcount underflow for the listener\nand double-free of the reqsk.\n\nLet's remove reqsk_fastopen_remove() in tcp_conn_request().\n\nNote that other callers make sure tp->fastopen_rsk is not NULL.\n\n[0]:\nrefcount_t: underflow; use-after-free.\nWARNING: CPU: 12 PID: 5563 at lib/refcount.c:28 refcount_warn_saturate (lib/refcount.c:28)\nModules linked in:\nCPU: 12 UID: 0 PID: 5563 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\nRIP: 0010:refcount_warn_saturate (lib/refcount.c:28)\nCode: ab e8 8e b4 98 ff 0f 0b c3 cc cc cc cc cc 80 3d a4 e4 d6 01 00 75 9c c6 05 9b e4 d6 01 01 48 c7 c7 e8 df fb ab e8 6a b4 98 ff <0f> 0b e9 03 5b 76 00 cc 80 3d 7d e4 d6 01 00 0f 85 74 ff ff ff c6\nRSP: 0018:ffffa79fc0304a98 EFLAGS: 00010246\nRAX: d83af4db1c6b3900 RBX: ffff9f65c7a69020 RCX: d83af4db1c6b3900\nRDX: 0000000000000000 RSI: 00000000ffff7fff RDI: ffffffffac78a280\nRBP: 000000009d781b60 R08: 0000000000007fff R09: ffffffffac6ca280\nR10: 0000000000017ffd R11: 0000000000000004 R12: ffff9f65c7b4f100\nR13: ffff9f65c7d23c00 R14: ffff9f65c7d26000 R15: ffff9f65c7a64ef8\nFS: 00007f9f962176c0(0000) GS:ffff9f65fcf00000(0000) knlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000200000000180 CR3: 000000000dbbe006 CR4: 0000000000372ef0\nCall Trace:\n \n tcp_conn_request (./include/linux/refcount.h:400 ./include/linux/refcount.h:432 ./include/linux/refcount.h:450 ./include/net/sock.h:1965 ./include/net/request_sock.h:131 net/ipv4/tcp_input.c:7301)\n tcp_rcv_state_process (net/ipv4/tcp_input.c:6708)\n tcp_v6_do_rcv (net/ipv6/tcp_ipv6.c:1670)\n tcp_v6_rcv (net/ipv6/tcp_ipv6.c:1906)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:438)\n ip6_input (net/ipv6/ip6_input.c:500)\n ipv6_rcv (net/ipv6/ip6_input.c:311)\n __netif_receive_skb (net/core/dev.c:6104)\n process_backlog (net/core/dev.c:6456)\n __napi_poll (net/core/dev.c:7506)\n net_rx_action (net/core/dev.c:7569 net/core/dev.c:7696)\n handle_softirqs (kernel/softirq.c:579)\n do_softirq (kernel/softirq.c:480)\n ", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "7ec092a91ff351dcde89c23e795b73a328274db6", "status": "affected", "versionType": "git", "lessThan": "e359b742eac1eac75cff4e38ee2e8cea492acd9b" }, { "version": "a4378dedd6e07e62f2fccb17d78c9665718763d0", "status": "affected", "versionType": "git", "lessThan": "ff6a8883f96a5bc74241ce5b3d431a6dcfa2124d" }, { "version": "33a4fdf0b4a25f8ce65380c3b0136b407ca57609", "status": "affected", "versionType": "git", "lessThan": "eb85ad5f23268d64b037bfb545cbcba3752f90c7" }, { "version": "17d699727577814198d744d6afe54735c6b54c99", "status": "affected", "versionType": "git", "lessThan": "643a94b0cf767325e953591c212be2eb826b9d7f" }, { "version": "dfd06131107e7b699ef1e2a24ed2f7d17c917753", "status": "affected", "versionType": "git", "lessThan": "422c1c173c39bbbae1e0eaaf8aefe40b2596233b" }, { "version": "fa4749c065644af4db496b338452a69a3e5147d9", "status": "affected", "versionType": "git", "lessThan": "c11ace909e873118295e9eb22dc8c58b0b50eb32" }, { "version": "45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01", "status": "affected", "versionType": "git", "lessThan": "64dc47a13aa3d9daf7cec29b44dca8e22a6aea15" }, { "version": "45c8a6cc2bcd780e634a6ba8e46bffbdf1fc5c01", "status": "affected", "versionType": "git", "lessThan": "2e7cbbbe3d61c63606994b7ff73c72537afe2e1c" }, { "version": "ae313d14b45eca7a6bb29cb9bf396d977e7d28fb", "status": "affected", "versionType": "git" }, { "version": "5.4.300", "status": "affected", "versionType": "semver", "lessThan": "5.4.301" }, { "version": "5.10.245", "status": "affected", "versionType": "semver", "lessThan": "5.10.246" }, { "version": "5.15.194", "status": "affected", "versionType": "semver", "lessThan": "5.15.195" }, { "version": "6.1.154", "status": "affected", "versionType": "semver", "lessThan": "6.1.157" }, { "version": "6.6.108", "status": "affected", "versionType": "semver", "lessThan": "6.6.113" }, { "version": "6.12.49", "status": "affected", "versionType": "semver", "lessThan": "6.12.54" }, { "version": "6.16.9", "status": "affected", "versionType": "semver", "lessThan": "6.17" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.17", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.17" }, { "version": "5.4.301", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.246", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.195", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.157", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.113", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.54", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.17.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.17.*" }, { "version": "6.18", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }