--- id: CVE-2024-26923 title: |- In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection.… summary: |- In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection.… severity: high cvss: 7.8 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' cwe: - CWE-362 vendor: linux product: linux_kernel affected: - 'linux_kernel >= 2.6.23, < 4.19.314' - 'linux_kernel >= 4.20, < 5.4.275' - 'linux_kernel >= 5.5, < 5.10.216' - 'linux_kernel >= 5.11, < 5.15.156' - 'linux_kernel >= 5.16, < 6.1.87' - 'linux_kernel >= 6.2, < 6.6.28' - 'linux_kernel >= 6.7, < 6.8.7' - linux_kernel = 6.9 - debian_linux = 10.0 patched: - linux_kernel 6.8.7 published: '2024-04-25' updated: '2026-10-15' sourceUpdated: '2026-10-15T01:17:31.997' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2024-26923' references: - url: 'https://git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://cert-portal.siemens.com/productcert/html/ssa-265688.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e - url: 'https://cert-portal.siemens.com/productcert/html/ssa-613116.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e tags: - nvd - cve.org epss: 0.00207 epssPercentile: 0.10089 ingestedAt: '2026-10-15T03:30:12.661Z' ssvc: exploitation: none automatable: 'no' technicalImpact: total timestamp: '2024-07-02T00:00:00+00:00' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list. sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- ----------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0 NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V became in-flight // V count=2 inflight=1 close(V) // V count=1 inflight=1 // GC candidate condition met for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates // gc_candidates={L, V} for u in gc_candidates: scan_children(u, dec_inflight) // embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) If there is a GC-candidate listening socket, lock/unlock its state. This makes GC wait until the end of any ongoing connect() to that socket. After flipping the lock, a possibly SCM-laden embryo is already enqueued. And if there is another embryo coming, it can not possibly carry SCM_RIGHTS. At this point, unix_inflight() can not happen because unix_gc_lock is already taken. Inflight graph remains unaffected. ## Affected - `linux_kernel >= 2.6.23, < 4.19.314` - `linux_kernel >= 4.20, < 5.4.275` - `linux_kernel >= 5.5, < 5.10.216` - `linux_kernel >= 5.11, < 5.15.156` - `linux_kernel >= 5.16, < 6.1.87` - `linux_kernel >= 6.2, < 6.6.28` - `linux_kernel >= 6.7, < 6.8.7` - `linux_kernel = 6.9` - `debian_linux = 10.0` ## Remediation Upgrade past the affected range: - `linux_kernel 6.8.7`