Bug 2507183 (CVE-2026-64518)

Summary: CVE-2026-64518 kernel: tcp: Fix out-of-bounds access for twsk in tcp_ao_established_key()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's TCP implementation. An out-of-bounds access vulnerability exists when the `lockdep_sock_is_held()` function is called with a `tcp_timewait_sock` object. This occurs because the `tcp_timewait_sock` object lacks the necessary `sk->sk_lock`, leading to an incorrect lockdep annotation. This issue could potentially lead to system instability or other undefined behavior.
 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:
Embargoed:

Description OSIDB Bzimport 2026-07-25 10:09:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tcp: Fix out-of-bounds access for twsk in tcp_ao_established_key().

lockdep_sock_is_held() was added in tcp_ao_established_key()
by the cited commit.

It can be called from tcp_v[46]_timewait_ack() with twsk.

Since it does not have sk->sk_lock, the lockdep annotation
results in out-of-bound access.

  $ pahole -C tcp_timewait_sock vmlinux | grep size
  	/* size: 288, cachelines: 5, members: 8 */
  $ pahole -C sock vmlinux | grep sk_lock
  	socket_lock_t              sk_lock;              /*   440   192 */

Let's not use lockdep_sock_is_held() for TCP_TIME_WAIT.
Comment 1 TEJ RATHI 2026-07-29 12:49:01 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072538-CVE-2026-64518-7bc3@gregkh/T