Buffer overflow in Exim
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 overflow may happen. This can be used to execute code remotely.
Vulnerability class: Buffer Overflow
EPSS: 0.821 (99.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Exim
- Canonical Ubuntu_linux — versions 14.04, 16.04, 17.10
- Debian Debian_linux — versions 7.0, 8.0, 9.0
- N/a — versions n/a
Weakness classification (CWE)
CISA KEV (Known Exploited Vulnerabilities)
This CVE is on the CISA KEV catalog, added on . CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.
BOD 22-01 due date: .
Required action: Apply updates per vendor instructions.
Known ransomware campaign use: yes.
Public proof-of-concept exploits
References
- cve@mitre.org (x_refsource_CONFIRM, Vendor Advisory)
- cve@mitre.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- cve@mitre.org (x_refsource_UBUNTU, vendor-advisory, Third Party Advisory)
- cve@mitre.org (x_refsource_CONFIRM, Mailing List, Third Party Advisory)
- cve@mitre.org (VDB Entry, Third Party Advisory, vdb-entry, x_refsource_SECTRACK, Broken Link)
- cve@mitre.org (vendor-advisory, Mailing List, Third Party Advisory, x_refsource_DEBIAN)
- cve@mitre.org (Exploit, VDB Entry, Third Party Advisory, exploit, x_refsource_EXPLOIT-DB)
- cve@mitre.org (mailing-list, x_refsource_MLIST, Mailing List, Third Party Advisory)
- cve@mitre.org (x_refsource_CONFIRM, Patch)
- cve@mitre.org (Exploit, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2018-6789?
- CVE-2018-6789 is a critical-severity vulnerability in Exim, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2018-02-08.
- How severe is CVE-2018-6789?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2018-6789 known to be exploited?
- Yes. CVE-2018-6789 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating it is being actively exploited. 24 public proof-of-concept repositories are indexed.