CVE-2026-43964

Postfix before 3.8.16, 3.9 before 3.9.10, and 3.10 before 3.10.9 sometimes allows a buffer over-read and process crash via an enhanced status code that lacks text after the third number.

Published: 2026-05-04 Last update: 2026-05-11 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-43964 is rated Low Risk (23.3/100): CVSS Low severity, with low exploitation likelihood (EPSS 0.32%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-43964

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.32% +0.27%
2 2026-05-10 0.04% 0.05% +0.01%
3 2026-05-05 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-43964

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
3.7 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.2 1.4 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-43964

GitHub Security Advisory for CVE-2026-43964

GHSA-c4gx-p7gq-g6hp · Severity: low — Postfix before 3.8.16, 3.9 before 3.9.10, and 3.10 before 3.10.9 sometimes allows a buffer over...

OS Trackers for CVE-2026-43964

vendor priority summary link
debian not yet assigned CVE-2026-43964 not yet assigned priority: Debian including 1 source packages (postfix), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-43964
suse medium — https://www.suse.com/security/cve/CVE-2026-43964/
ubuntu medium CVE-2026-43964 medium priority: Ubuntu including 1 source packages (postfix), 9 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): needs-triage 5, released 4. https://ubuntu.com/security/CVE-2026-43964

Affected software / configurations for CVE-2026-43964

Vendor Product Version Raw CPE
postfix postfix < 3.8.16 cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*
postfix postfix >= 3.9.0, < 3.9.10 cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*
postfix postfix >= 3.10.0, < 3.10.9 cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*

References for CVE-2026-43964

URL Tags
https://www.mail-archive.com/[email protected]/msg00110.html Mailing List Third Party Advisory
http://www.openwall.com/lists/oss-security/2026/05/04/30 Mailing List Third Party Advisory
cvelogic Threat Intelligence