CVE-2023-4874Network attack vector

Client crash via invalid RFC 2047 decoding

Published Sep 9, 2023 · Updated Jul 25, 2026

Null-pointer dereference in Mutt after 1.5.2 and before 2.2.12 allows remote attackers to crash the client via a crafted email header. The RFC 2047 Base64 decoder accepts illegal characters and can reduce an entire header field to an empty result, violating downstream nonempty-header assumptions. The recipient must view the crafted message; the resulting null dereference interrupts that client process without reported data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability0.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Null-pointer dereference in Mutt after 1.5.2 and before 2.2.12 allows remote attackers to crash the client via a crafted email header. The RFC 2047 Base64 decoder accepts illegal characters and can reduce an entire header field to an empty result, violating downstream nonempty-header assumptions. The recipient must view the crafted message; the resulting null dereference interrupts that client process without reported data disclosure or modification.

The record

CVE
CVE-2023-4874
Published
Sep 9, 2023
Updated
Jul 25, 2026
Vendor
Mutt
Product
Mutt
Classifications
CWE-476, CWE-475
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.5.2 <2.2.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mutt · Muttversion=1.5.2 <2.2.12

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
CWE-475Undefined Behavior for Input to API

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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