{"cve":"CVE-2024-26923","nvd":{"published":"2024-04-25T06:15:57.160","modified":"2026-10-15T01:17:31.997","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix garbage collector racing against connect()\n\nGarbage collector does not take into account the risk of embryo getting\nenqueued during the garbage collection. If such embryo has a peer that\ncarries SCM_RIGHTS, two consecutive passes of scan_children() may see a\ndifferent set of children. Leading to an incorrectly elevated inflight\ncount, and then a dangling pointer within the gc_inflight_list.\n\nsockets are AF_UNIX/SOCK_STREAM\nS is an unconnected socket\nL is a listening in-flight socket bound to addr, not in fdtable\nV's fd will be passed via sendmsg(), gets inflight count bumped\n\nconnect(S, addr)\tsendmsg(S, [V]); close(V)\t__unix_gc()\n----------------\t-------------------------\t-----------\n\nNS = unix_create1()\nskb1 = sock_wmalloc(NS)\nL = unix_find_other(addr)\nunix_state_lock(L)\nunix_peer(S) = NS\n\t\t\t// V count=1 inflight=0\n\n \t\t\tNS = unix_peer(S)\n \t\t\tskb2 = sock_alloc()\n\t\t\tskb_queue_tail(NS, skb2[V])\n\n\t\t\t// V became in-flight\n\t\t\t// V count=2 inflight=1\n\n\t\t\tclose(V)\n\n\t\t\t// V count=1 inflight=1\n\t\t\t// GC candidate condition met\n\n\t\t\t\t\t\tfor u in gc_inflight_list:\n\t\t\t\t\t\t  if (total_refs == inflight_refs)\n\t\t\t\t\t\t    add u to gc_candidates\n\n\t\t\t\t\t\t// gc_candidates={L, V}\n\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  scan_children(u, dec_inflight)\n\n\t\t\t\t\t\t// embryo (skb1) was not\n\t\t\t\t\t\t// reachable from L yet, so V's\n\t\t\t\t\t\t// inflight remains unchanged\n__skb_queue_tail(L, skb1)\nunix_state_unlock(L)\n\t\t\t\t\t\tfor u in gc_candidates:\n\t\t\t\t\t\t  if (u.inflight)\n\t\t\t\t\t\t    scan_children(u, inc_inflight_move_tail)\n\n\t\t\t\t\t\t// V count=1 inflight=2 (!)\n\nIf there is a GC-candidate listening socket, lock/unlock its state. This\nmakes GC wait until the end of any ongoing connect() to that socket. After\nflipping the lock, a possibly SCM-laden embryo is already enqueued. And if\nthere is another embryo coming, it can not possibly carry SCM_RIGHTS. At\nthis point, unix_inflight() can not happen because unix_gc_lock is already\ntaken. Inflight graph remains unaffected.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3","https://git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f","https://git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51","https://git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9","https://git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423"],"products":["debian:debian_linux","linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:49:08.435428910+00:00"},"epss":{"cve":"CVE-2024-26923","score":0.00207,"percentile":0.10715,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}