Expired Pointer Dereference Affecting bpftool package, versions <1:6.1.188-233.393.amzn2023


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.58% (47th percentile)

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  • Snyk IDSNYK-AMZN2023-BPFTOOL-20931007
  • published14 Oct 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

CVE-2026-89637  (opens in a new tab)
CWE-825  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 bpftool to version 1:6.1.188-233.393.amzn2023 or higher.
This issue was patched in ALAS2023-2026-3183.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bpftool package and not the bpftool package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix UAF and buffer leak in cifs_check_trans2() for malformed secondary T2

When a valid primary TRANSACT2 response has been received (mid->resp_buf set, mid->multiRsp true) and a subsequent secondary response causes cifs_check_trans2() to return false -- either because the SMB header is invalid (malformed != 0) or because check2ndT2() rejects the PDU -- handle_mid() overwrites mid->resp_buf with the new buffer (leaking the primary buffer) and, because mid->multiRsp is set, skips the server->smallbuf/bigbuf NULL-out. When the user thread frees mid->resp_buf, server->smallbuf or server->bigbuf is left dangling; the demux thread reuses it for the next packet, resulting in a use-after-free.

Combine both early-exit conditions and, when mid->multiRsp is already set, abort the pending transaction inline: set multiEnd, call dequeue_mid() with malformed=true, and return true so handle_mid() exits without touching mid->resp_buf or the server buffer pointers.

CVSS Base Scores

version 3.1