An issue was discovered in the base64d function in the SMTP listener in Exim before…
Priority CRITICAL 100Exploited in the wildCWE-120Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Will not fix Red Hat: no fix planned
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat. Impact type from CWE-120 and the CVSS impact.
Summary
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.
Why it matters now
Exploitation Active In CISA KEV since 2021-11-03CISA due date 2022-05-03Known ransomware use
EPSS 0.82137 99th percentileScored 2026-11-07
Public exploit Yes 4 exploit referencesTagged by the CNA and NVD
Fix Will not fix Red Hat: no fix planned
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Active
- Automatable
- Yes
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 7
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:* | before 4.90.1 | Vulnerable | Exim |
| cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:* | 7.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* | 8.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* | 9.0 | Vulnerable | Debian |
| cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:* | 14.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:* | 16.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:* | 17.10 | Vulnerable | Canonical |
- cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:* Versions before 4.90.1 Vulnerable ·Exim
- cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:* Versions 7.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:* Versions 8.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian
- cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:* Versions 14.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:* Versions 16.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:* Versions 17.10 Vulnerable ·Canonical
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Critical. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Will not fix |
Timeline
- 2021-11-03 Added to CISA KEV
- 2026-10-02 Threatist record created from CVE-2018-6789
- 2026-10-03 Alias added: GHSA-868p-wr6f-7jfr
References
Exploit 4
More Exim vulnerabilities
- TI-2019-12627 Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than… KEVCVSS 3.1CRITICAL 9.8
- TI-2019-07471 OS command injection in exim KEVCVSS 3.1CRITICAL 9.8
- TI-2010-04077 Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70… KEVCVSS 3.1CRITICAL 9.8
- TI-2010-04078 Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of… KEVCVSS 3.1HIGH 7.8
- TI-2025-19707 SQL injection in Exim CVSS 3.1CRITICAL 9.8
- TI-2023-22483 Out-of-bounds write in Exim CVSS 3.0CRITICAL 9.8
Sources
- CVE-2018-6789 · CVE Program
- CVE-2018-6789 · NVD
- CISA Known Exploited Vulnerabilities
- FIRST EPSS
- GHSA-868p-wr6f-7jfr · GitHub Advisory Database · CC BY 4.0
- CVE-2018-6789 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences