CISA KEV · Known exploitedCritical

CVE-2018-6789

Exim

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
9.8
EPSS
81.7%
99.6% percentile
CISA KEV
Listed
Published
2018.02.09
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability81.7%
Technical severityCVSS 9.8

Vulnerability overview

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.

Affected product and versions

Product
Exim
Affected versions
< 4.90.1, 7.0, 8.0, 9.0, 14.04, 16.04, 17.10
Fixed versions
4.90.1

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

Apply updates per vendor instructions.

Due date: 2022.05.03
  1. 1
    Identify

    Confirm that Exim and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-119, CWE-120
KEV added
2021.11.03
Ransomware use
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