CVE-2018-6789

CRITICALNVD 9.89.8—Trending — 5 sources updated this weekExploited in the wild

9.8

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 v3: 9.8
EG Score: 9.8(high)
EPSS: 99.4%
KEV: ⚠ Exploited

Published

February 8, 2018

Last Modified

November 7, 2025

Advisory Details (9)

Auto-updated Jun 1, 2026

Patch available.

generic Patch Available

[SECURITY] [DLA 1274-1] exim4 security update

https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html

generic

exim - Exim Forgejo

https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1

generic

https://exim.org/static/doc/security/CVE-2018-6789.txt

generic

Exim Off-by-one RCE: Exploiting CVE-2018-6789 with Fully Mitigations Bypassing | DEVCORE

https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/

generic

http://www.securitytracker.com/id/1040461

generic

http://www.securityfocus.com/bid/103049

generic

oss-security - CVE-2018-6789 Exim 4.90 and earlier: buffer overflow

http://www.openwall.com/lists/oss-security/2018/02/07/2

generic

Packet Storm

http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html

generic

oss-security - Exim 4.90.1 released. (Was: CVE-2018-6789 Exim 4.90 and earlier: buffer overflow)

http://openwall.com/lists/oss-security/2018/02/10/2

Patch Availability(1)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
ubuntu	eximon4 (4.86.2-2ubuntu2.3) @ xenial	2026-06-04	ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

UbuntuUSN-3565-1MEDIUM
Exim vulnerability

Data Freshness Timeline

(refreshed 20× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-04 00:52 UTCEG score recompute
2026-06-04 00:52 UTCVendor advisory
2026-06-04 00:52 UTCGHSA enrichment
2026-06-03 21:05 UTCEG score recompute
2026-06-03 21:05 UTCVendor advisory
2026-06-03 21:05 UTCGHSA enrichment
2026-06-03 19:09 UTCkev_newly_listed
2026-06-03 17:17 UTCEG score recompute
2026-06-03 17:17 UTCVendor advisory
2026-06-03 17:17 UTCGHSA enrichment
2026-06-03 13:30 UTCEG score recompute
2026-06-03 13:30 UTCVendor advisory
2026-06-03 13:30 UTCGHSA enrichment
2026-06-03 09:42 UTCEG score recompute
2026-06-03 09:42 UTCVendor advisory
2026-06-03 09:42 UTCGHSA enrichment
2026-06-03 05:55 UTCEG score recompute
2026-06-03 05:55 UTCVendor advisory
2026-06-03 05:55 UTCGHSA enrichment
2026-06-03 02:08 UTCEG score recompute

Publicly available exploits

(6 references)

Working exploit code is in the public domain (4 GitHub PoCs) (2 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

GitHub PoCthistehneisen/CVE-2018-6789-Python3
First seen Aug 5, 2023
Exim < 4.90.1 RCE Vulnerability remake for Python3 with arguments passed from CLI
Open source ↗
GitHub PoCmartinclauss/exim-rce-cve-2018-6789
First seen Mar 2, 2020
This repository provides a learning environment to understand how an Exim RCE exploit for CVE-2018-6789 works.
Open source ↗
GitHub PoCsynacktiv/Exim-CVE-2018-6789
First seen Oct 10, 2019
PoC materials to exploit CVE-2018-6789
Open source ↗
GitHub PoCberaphin/CVE-2018-6789
First seen Nov 8, 2018
Open source ↗
Exploit-DBEDB-45671
First seen Oct 24, 2018
exim 4.90 - Remote Code Execution
Open source ↗
Exploit-DBEDB-44571
First seen May 2, 2018
Exim < 4.90.1 - 'base64d' Remote Code Execution
Open source ↗

Frequently asked(6)

What is CVE-2018-6789?

CVE-2018-6789 is a critical vulnerability published on February 8, 2018. 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.

When was CVE-2018-6789 disclosed?

CVE-2018-6789 was first published in the National Vulnerability Database on February 8, 2018, with the most recent update on November 7, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2018-6789 actively exploited?

Yes. CISA added CVE-2018-6789 to the Known Exploited Vulnerabilities catalog on November 3, 2021, affecting Exim Exim. KEV listing indicates confirmed exploitation in the wild; this CVE warrants immediate patching attention.

What is the CVSS score of CVE-2018-6789?

CVE-2018-6789 has a CVSS v3 base score of 9.8 (NVD).

Which products are affected by CVE-2018-6789?

CVE-2018-6789 affects Exim Exim. The full affected-products list, including version ranges and fixed versions, is shown in the Affected Packages section of this page.

How do I remediate CVE-2018-6789?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-6789, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2018-6789

Explore →

Is Your Infrastructure Affected by CVE-2018-6789?

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CVE-2018-6789

Published

Last Modified

Advisory Details (9)

[SECURITY] [DLA 1274-1] exim4 security update

exim - Exim Forgejo

Exim Off-by-one RCE: Exploiting CVE-2018-6789 with Fully Mitigations Bypassing | DEVCORE

oss-security - CVE-2018-6789 Exim 4.90 and earlier: buffer overflow

Packet Storm

oss-security - Exim 4.90.1 released. (Was: CVE-2018-6789 Exim 4.90 and earlier: buffer overflow)

Patch Availability(1)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

Publicly available exploits

Frequently asked(6)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2018-6789?

Same vendor

Same CWE

CVE-2018-6789

📅 Published

🔄 Last Modified

📋 Advisory Details (9)

[SECURITY] [DLA 1274-1] exim4 security update

exim - Exim Forgejo

Exim Off-by-one RCE: Exploiting CVE-2018-6789 with Fully Mitigations Bypassing | DEVCORE

oss-security - CVE-2018-6789 Exim 4.90 and earlier: buffer overflow

Packet Storm

oss-security - Exim 4.90.1 released. (Was: CVE-2018-6789 Exim 4.90 and earlier: buffer overflow)

Patch Availability(1)

Weakness Classification(2)

All Vendor Advisories

Data Freshness Timeline

Publicly available exploits

❓ Frequently asked(6)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2018-6789?

🔗 Related CVEs(same vendor + same CWE)

Same vendor

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Published

Last Modified

Advisory Details (9)

Frequently asked(6)

Related CVEs(same vendor + same CWE)