Bug 2524478 (CVE-2026-80521)
| Summary: | CVE-2026-80521 kernel: af_unix: Unlink scc_entry in unix_del_edge() | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security <prodsec-ir-bot> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | akito5623, rhel-process-autobot, watson-tool-maintainers |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
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| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel's `af_unix` component. A race condition during concurrent `send()` and `close()` operations can lead to the garbage collector (GC) partially freeing a Strongly Connected Component (SCC). This inconsistent state may cause subsequent GC operations to iterate over a partially freed entry, potentially leading to system instability or a denial of service.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
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Upstream advisory: https://lore.kernel.org/linux-cve-announce/2026082601-CVE-2026-80521-2b35@gregkh/T Public exploit code related to this issue appears to be available: Exploit: https://github.com/Markakd/Container_escape Demonstration video: https://x.com/Markak_/status/2102478278594543807 However, the demonstration video does not clearly identify whether it is specifically demonstrating CVE-2026-80521, CVE-2026-52910, or a combination of both issues. Upstream patch / CVE announcement: https://lore.kernel.org/linux-cve-announce/2026082601-CVE-2026-80521-2b35@gregkh/T/#u Could Red Hat please verify whether the published exploit affects RHEL kernels and whether this exploit is specifically applicable to CVE-2026-80521? If a demonstration video specifically showing exploitation of CVE-2026-80521 is available, I would also be interested in reviewing it. |
In the Linux kernel, the following vulnerability has been resolved: af_unix: Unlink scc_entry in unix_del_edge(). Kyle Zeng reported that GC could free a dead SCC partially. The scenario is as follows: 1) Create two SCCs: X -. A <-> B ^--' 2) Run the following concurrently: 2-1) send() sk-B to sk-B from sk-X 2-2) close() both A and B At 2-1), there is a small window where unix_add_edges() publishes a new edge (B <-> B) to GC but its skb is not queued by skb_queue_tail(). If 2-2) completes before skb_queue_tail() and GC is triggered, it judges A <-> B as dead, but B is not freed because GC cannot collect the not-yet-queued skb holding the B <-> B edge. X -. A <-> B -. This edge is visible ^--' ^..' but skb is not This itself is not a problem since the next GC run will judge B as dead as well and free it finally. X -. A <.> B -. ^--' ^--' However, X's SCC forces the next GC to call unix_walk_scc_fast(), and it iterates over A through B's scc_entry. Let's unlink scc_entry before freeing the vertex in unix_del_edge().