CVE-2026-40684
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
02 Description
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
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.36% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 29.7% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-04-30 00:00Z6 MO AGO
- Last updated
- 2026-05-01 17:22Z6 MO AGO
- Reserved
- 2026-04-14
- Assigning CNA
- mitre
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 5.9)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weaknesses
- CWE-684Incorrect Provision of Specified FunctionalityClass
- Data version
- 5.2
- Document digest
- bbb0263e0d45ba713360467c44685cf52116b44ca0a100f52211f2c1c30e1d08
05 Affected products
06 References
- www.openwall.comhttps://www.openwall.com/lists/oss-security/2026/04/30/21
- exim.orghttps://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40684.assessment
- code.exim.orghttps://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
- exim.orghttps://exim.org/static/doc/security/CVE-2026-40684.txt
- www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/05/01/11
07 Fixed in
Debian 12
- exim4 Fixed in 4.96-15+deb12u9
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- exim4 Fixed in 4.98.2-1+deb13u2
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- exim4 Fixed in 4.99.2-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.