CVE-2018-6789
Exim Buffer Overflow Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 3 May 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 82.14% probability · 100th percentile
- Public exploits
- 2 in Exploit-DB · first 2 May 2018
- CISA KEV
- Listed 3 November 2021 · due 3 May 2022 · used in ransomware campaigns
- Weakness
- CWE-120
- Affected
- exim/exim · debian/debian linux · canonical/ubuntu linux
- Source
- cve@mitre.org
EPSS 82.1% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2018-6789
Public exploits (2)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://openwall.com/lists/oss-security/2018/02/10/2Mailing List, Third Party Advisory
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.htmlExploit, Third Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2018/02/07/2Mailing List, Third Party Advisory
- http://www.securityfocus.com/bid/103049Broken Link, Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040461Broken Link, Third Party Advisory, VDB Entry
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/Exploit, Third Party Advisory
- https://exim.org/static/doc/security/CVE-2018-6789.txtVendor Advisory
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1Patch
- https://lists.debian.org/debian-lts-announce/2018/02/msg00009.htmlMailing List, Third Party Advisory
- https://usn.ubuntu.com/3565-1/Third Party Advisory
- https://www.debian.org/security/2018/dsa-4110Mailing List, Third Party Advisory
- https://www.exploit-db.com/exploits/44571/Exploit, Third Party Advisory, VDB Entry
- https://www.exploit-db.com/exploits/45671/Exploit, Third Party Advisory, VDB Entry
- http://openwall.com/lists/oss-security/2018/02/10/2Mailing List, Third Party Advisory
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.htmlExploit, Third Party Advisory, VDB Entry
- http://www.openwall.com/lists/oss-security/2018/02/07/2Mailing List, Third Party Advisory
- http://www.securityfocus.com/bid/103049Broken Link, Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1040461Broken Link, Third Party Advisory, VDB Entry
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/Exploit, Third Party Advisory
- https://exim.org/static/doc/security/CVE-2018-6789.txtVendor Advisory
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1Patch
- https://lists.debian.org/debian-lts-announce/2018/02/msg00009.htmlMailing List, Third Party Advisory
- https://usn.ubuntu.com/3565-1/Third Party Advisory
- https://www.debian.org/security/2018/dsa-4110Mailing List, Third Party Advisory
- https://www.exploit-db.com/exploits/44571/Exploit, Third Party Advisory, VDB Entry
- https://www.exploit-db.com/exploits/45671/Exploit, Third Party Advisory, VDB Entry
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-6789US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.