CVE-2024-26923: Linux kernel · af_unix: Fix garbage collector racing against connect()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 4.4.0-1134.140 : patch Linux kernel soon.
Data as of 28 Oct 2026, 10:59 UTC
- Patch
- Available – fixed in 4.4.0-1134.140, 4.15.0-1179.194~14.04.1, 4.4.0-257.291~14.04.1 +99
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Apr 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-6893-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6893-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6900-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-3 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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.
References
- ubuntu.com/security/CVE-2024-26923 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-26923 (opens in a new tab)
- git.kernel.org/linus/47d8ac011fe1c9251070e1bd64cb10b48193ec51 (opens in a new tab)
- git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51 (opens in a new tab)
- git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c (opens in a new tab)
- git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9 (opens in a new tab)
- git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009 (opens in a new tab)
- git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51 (opens in a new tab)
- ubuntu.com/security/notices/USN-6893-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6893-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-6900-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-6896-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6895-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-6898-3 (opens in a new tab)