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CVE-2026-53389

HIGH 7.8

Published 2026-07-19 · Last modified 2026-07-20

In the Linux kernel, the following vulnerability has been resolved: net/tcp-ao: fix use-after-free of key in del_async path In tcp_ao_delete_key(), the del_async path skips the current_key and rnext_key validity checks present in the synchronous path, assuming these pointers are always NULL on LISTEN sockets. However, if a key was added with set_current=1/set_rnext=1 while the socket was in CLOSE state, current_key and rnext_key will be non-NULL after listen() transitions the socket to LISTEN. When such a key is deleted with del_async=1, hlist_del_rcu() and call_rcu() free the key without clearing the dangling pointers. After the RCU grace period, getsockopt(TCP_AO_INFO) dereferences current_key->sndid and rnext_key->rcvid from freed slab memory. Clear current_key and rnext_key in the del_async path when they reference the key being deleted.

ELEVATED IMPACT

Severe if exploited (CVSS 7.8), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.1%chance of exploitation in 30 days · 3rd percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

7.8CVSS 3.1 · HIGH

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ⚠Access: Requires local access to the host
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-53389/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-53389/poc.json

Affected

Vendors Linux

Products Linux

Weakness (CWE)

Not classified.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

All CVSS metrics

  • HIGH 7.8 v3.1 · CNA Primary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  • HIGH 7.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

Technical & other

Sources: NVD · CVE.org · EPSS