Security Resilience

CVE-2018-6789

Memory Safety in Debian Linux 7.0 … 9.0

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linkedMemory Safety
Published
08 February 2018
Modified
07 November 2025
KEV Added
03 November 2021
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.82 99.7th percentile
Risk Priority 97 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2018-6789 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Debian Debian Linux. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique NTDS (T1003.003); ranked in the top 0.3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

The vulnerability is a buffer overflow (CWE-120) in the base64d function within the SMTP listener component of Exim versions prior to 4.90.1. It was assigned CVE-2018-6789 with a CVSS v3.1 score of 9.8, reflecting network-accessible attack conditions that require no authentication or user interaction.

An unauthenticated remote attacker can exploit the flaw by sending a specially crafted message to the SMTP listener, triggering the overflow to achieve arbitrary code execution on the affected server with full confidentiality, integrity, and availability impact.

Advisories referenced in public disclosure lists indicate that the issue is resolved by upgrading to Exim 4.90.1 or later. No additional real-world exploitation details or AI/ML considerations are provided in the source data.

EU & UK References

Vulnerability Data

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.

CWE(s)
CWE-120
KEV Date Added
03 November 2021

Related Threats

Threat-Actor AttributionAI

Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
APT1 (G0006)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
Deep Panda (G0009)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
APT3 (G0022)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
Winnti Group (G0044)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
menuPass (G0045)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
Leviathan (G0065)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
APT19 (G0073)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
APT41 (G0096)
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA
AnonOps
Potential for China Cyber Response to Heightened U.S.–China Tensions | CISA

MITRE ATT&CK Enterprise Techniques

T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1003.008 /etc/passwd and /etc/shadow Credential Access
Adversaries may attempt to dump the contents of <code>/etc/passwd</code> and <code>/etc/shadow</code> to enable offline password cracking.
attack.mitre.org →
T1010 Application Window Discovery Discovery
Adversaries may attempt to get a listing of open application windows.
attack.mitre.org →
T1012 Query Registry Discovery
Adversaries may interact with the Windows Registry to gather information about the system, configuration, and installed software.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2019-10149Same product: Canonical Ubuntu Linuxboth on KEV
CVE-2010-4344Same product: Canonical Ubuntu Linuxboth on KEV
CVE-2019-16928Same product: Canonical Ubuntu Linuxboth on KEV
CVE-2010-4345Same product: Canonical Ubuntu Linuxboth on KEV
CVE-2004-0210Shared CWE-120both on KEV
CVE-2013-0641Shared CWE-120both on KEV
CVE-2023-33010Shared CWE-120both on KEV
CVE-2017-7269Shared CWE-120both on KEV
CVE-2022-37055Shared CWE-120both on KEV
CVE-2013-1331Shared CWE-120both on KEV

Affected Assets

exim
exim
≤ 4.90.1
debian
debian linux
7.0, 8.0, 9.0
canonical
ubuntu linux
14.04, 16.04, 17.10

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.2.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-27 Platform-independent Applications
addresses: CWE-120

Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-01 partial match
blocks

Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.

PR.PS-02 partial match
blocks

Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.

PR.PS-06 partial match
blocks

Secure development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References