CVE-2025-67896: exim Heap-based Buffer Overflow
CVSS: 9.8v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2025-67896DEBIAN-CVE-2025-67896
Published 14-12-2025Last modified 18-12-2025
Vulnerability summary
CVE-2025-67896 is a critical (CVSS 9.8) Heap-based Buffer Overflow vulnerability in exim. EPSS estimates a 0.47% chance of exploitation in the next 30 days, higher than 39.3% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (NVD)EPSS score
0.47%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 14-12-2025PublishedVulnerability first disclosed.
- 18-12-2025Last modifiedVulnerability information updated.
Description
Exim before 4.99.1, with certain non-default rate-limit configurations, allows a remote heap-based buffer overflow because database records are cast directly to internal structures without validation.
CVSS metrics
4 scores · 4 sources · 1 versionCritical 9.8Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSources4 sources · 6.4–9.8
- CVE.orgCNA7.0HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:LDiffers
- OSV · UbuntuEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:LDiffers
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.47%
Chance of exploitation in the next 30 days
Percentile
39%
Versus all other CVEs
30-day change
0.00 pp
From 0.47% on 19-09-2026
19-09-202619-10-2026
EPSS score0.47%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian1 product
- exim4< 4.99-7
Exim1 product
- exim≥ 4.99, < 4.99.1 | < 4.99.1
Ubuntu1 product
- exim4All versions (No fix recorded)
3 vendors · 3 products
References
8 links- www.openwall.com/lists/oss-security/2025/12/18/3Mailing List
