CVE-2018-6789
Critical 9.8 Exploited in the wild (KEV) Used in ransomware campaigns
Confirmed active exploitation — CISA KEV catalog
- Name
- Exim Buffer Overflow Vulnerability
- Added to catalog
- Remediation due date (US federal)
- Required action
- Apply updates per vendor instructions.
Description
An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.
Metrics
- CVSS 3.1
-
9.8 (CRITICAL)
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 82% (percentile: 100) as of 1 November 2026
- CWE
- CWE-120
Affected products
exim: exim; debian: debian linux; canonical: ubuntu linux
References
- https://exim.org/static/doc/security/CVE-2018-6789.txt Vendor Advisory
- https://exim.org/static/doc/security/CVE-2018-6789.txt Vendor Advisory
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1 Patch
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1 Patch
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html ExploitThird Party AdvisoryVDB Entry
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-e… ExploitThird Party Advisory
- https://www.exploit-db.com/exploits/44571/ ExploitThird Party AdvisoryVDB Entry
- https://www.exploit-db.com/exploits/45671/ ExploitThird Party AdvisoryVDB Entry
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html ExploitThird Party AdvisoryVDB Entry
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-e… ExploitThird Party Advisory