# CVE-2018-6789: Exim Buffer Overflow Vulnerability

> CVE-2018-6789: Exim Buffer Overflow Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2018-6789
Last updated: 2025-10-21T23:45:56Z

- Published: 2018-02-08 23:00 UTC · Updated: 2025-10-21 23:45 UTC · Assigner: mitre
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 82.1%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2021-11-03, federal due date 2022-05-03, ransomware use: Known

## 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.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Exim: Exim

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2018-6789)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2018-6789)
- [http://openwall.com/lists/oss-security/2018/02/10/2](http://openwall.com/lists/oss-security/2018/02/10/2)
- [http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html](http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html)
- [https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/](https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/)
- [https://exim.org/static/doc/security/CVE-2018-6789.txt](https://exim.org/static/doc/security/CVE-2018-6789.txt)
- [https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1](https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1)
- [https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html](https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html)
- [https://usn.ubuntu.com/3565-1/](https://usn.ubuntu.com/3565-1/)
- [https://www.debian.org/security/2018/dsa-4110](https://www.debian.org/security/2018/dsa-4110)
- [https://www.exploit-db.com/exploits/44571/](https://www.exploit-db.com/exploits/44571/)
- [https://www.exploit-db.com/exploits/45671/](https://www.exploit-db.com/exploits/45671/)
- [http://www.openwall.com/lists/oss-security/2018/02/07/2](http://www.openwall.com/lists/oss-security/2018/02/07/2)
- [http://www.securityfocus.com/bid/103049](http://www.securityfocus.com/bid/103049)
- [http://www.securitytracker.com/id/1040461](http://www.securitytracker.com/id/1040461)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2018-6789 · Markdown: https://rewindex.com/cve/CVE-2018-6789.md · JSON: https://rewindex.com/api/v1/cves/CVE-2018-6789 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:44:05.616Z