CVE-2018-6789
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…
- 9.8CriticalCVSS base score
- 82.1%Exploitation in 30 daysEPSS · top 0.3% of all CVEs
- YesKnown exploitedin CISA's KEV since 3 Nov 2021
- 2Public exploitsMetasploit, Nuclei and Exploit-DB
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Exim Buffer Overflow Vulnerability.
- Added
- 3 Nov 2021
- Fix due (US federal)
- 3 May 2022
- Used by ransomware
- Known
Apply updates per vendor instructions.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 3 Nov 2021.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list 2 Exploit-DB entries for it. 2 references of the record are tagged as an exploit. CISA's SSVC rates its exploitation: it is being exploited.
Show the exploits4
Exploit-DB2 entries
- exim 4.90 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 45671remote, linuxpublished 24 Oct 2018Not verified
- Exim < 4.90.1 - 'base64d' Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 44571remote, linuxpublished 2 May 2018Not verified
References tagged exploit2 references
- 44571 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 45671 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By mitre
- 2 days later
· 2 days later
Published
- 4 years later
· 4 years later
Added to CISA KEV
Known exploited, also by ransomware
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 82.1% · top 0.3% of all CVEs (9 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
n/a
- affected n/a
References
14
- https://exim.org/static/doc/security/CVE-2018-6789.txt (opens in a new tab)x_refsource_CONFIRMx_transferred
- [oss-security] 20180207 CVE-2018-6789 Exim 4.90 and earlier: buffer overflow (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- USN-3565-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
- http://openwall.com/lists/oss-security/2018/02/10/2 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 1040461 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_transferred
- DSA-4110 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
- 44571 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- [debian-lts-announce] 20180210 [SECURITY] [DLA 1274-1] exim4 security update (opens in a new tab)mailing-listx_refsource_MLISTx_transferred
- https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/ (opens in a new tab)x_refsource_MISCx_transferred
- 103049 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- 45671 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html (opens in a new tab)x_refsource_MISCx_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-6789 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2018-18536 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2018-6789)Record last updated .