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CVE-2026-40684

31
FAUCET Score

In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.

First published: Apr 30, 2026Last modified: May 1, 2026

Impacted Technologies

VendorProductVersion(s)CPE
>= 0, < 4.99.2CPE match
cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*
< 4.99.2CPE matchmatch criteria
cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.36%
Probability of exploitation in next 30 days
EPSS Percentile
28.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0036 is in the 9th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

openwall.com / lists/oss-security/2026/05/01/11
code.exim.org / exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
Patch
exim.org / static/doc/security/cve-2026-04.1/CVE2026-40684.assessment
Vendor Advisory
exim.org / static/doc/security/CVE-2026-40684.txt
Broken Link
openwall.com / lists/oss-security/2026/04/30/21
Mailing ListThird Party Advisory