Out-of-bounds read in Postfix - CVE-2026-43964
Published: May 19, 2026
Vulnerability identifier: #VU131864
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-43964
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Postfix.org
Affected software:
Postfix
Postfix
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an out-of-bounds read in Postfix status code processing when handling enhanced status codes that are not followed by additional text. A remote attacker can supply a specially crafted response or input to cause a denial of service.
This is confirmed with an access(5) table and with a DNSBL server TXT response when Postfix is configured with "$rbl_code $rbl_text" in rbl_reply_maps or default_rbl_reply, and is likely reachable through a policy server response.
How to mitigate CVE-2026-43964
Install security update from vendor's website.