CVE-2025-67478Network attack vector

Email misaddressing via unencoded comma

Published Feb 3, 2026 · Updated Feb 3, 2026

Email address miscomposition in Wikimedia Foundation CheckUser allows remote attackers to produce malformed headers via crafted usernames. UserMailer::quotedPrintable starts Q-encoding when non-ASCII bytes occur but leaves a comma literal inside the encoded-word instead of encoding it as =2C. A username containing both a comma and non-ASCII characters is required; published sources document incorrect address composition but do not establish message redirection or code execution.

CVSS severity8.8
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Email address miscomposition in Wikimedia Foundation CheckUser allows remote attackers to produce malformed headers via crafted usernames. UserMailer::quotedPrintable starts Q-encoding when non-ASCII bytes occur but leaves a comma literal inside the encoded-word instead of encoding it as =2C. A username containing both a comma and non-ASCII characters is required; published sources document incorrect address composition but do not establish message redirection or code execution.

The record

CVE
CVE-2025-67478
Published
Feb 3, 2026
Updated
Feb 3, 2026
Vendor
Wikimedia Foundation
Product
CheckUser
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 3, 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=* <1.39.14, 1.43.4, 1.44.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wikimedia Foundation · CheckUserversion=* <1.39.14, 1.43.4, 1.44.1

Published CVSS scores

0.0Wikimedia FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N/E:U
8.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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