CVE-2026-39934Network attack vector

Job-runner resource consumption via hidden-mentee mismatch

Published Apr 7, 2026 · Updated Apr 7, 2026

An infinite loop in Wikimedia Foundation GrowthExperiments 1.43.7, 1.44.4, and 1.45.2 allows remote attackers to consume job-runner resources. MentorStore::hasAnyMentees counts hidden mentees, while getMenteesByMentor omits them, so ReassignMenteesJob sees remaining work after retrieving none. The loop requires a resigned mentor with an assigned mentee account hidden by an oversighter; it repeatedly schedules empty jobs rather than causing a complete service outage.

CVSS severity6.9
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An infinite loop in Wikimedia Foundation GrowthExperiments 1.43.7, 1.44.4, and 1.45.2 allows remote attackers to consume job-runner resources. MentorStore::hasAnyMentees counts hidden mentees, while getMenteesByMentor omits them, so ReassignMenteesJob sees remaining work after retrieving none. The loop requires a resigned mentor with an assigned mentee account hidden by an oversighter; it repeatedly schedules empty jobs rather than causing a complete service outage.

The record

CVE
CVE-2026-39934
Published
Apr 7, 2026
Updated
Apr 7, 2026
Vendor
Wikimedia Foundation
Product
GrowthExperiments
Classifications
CWE-835, CAPEC-29, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 7, 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=1.43.7
  2. Affected versionversion=1.44.4
  3. Affected versionversion=1.45.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wikimedia Foundation · GrowthExperimentsversion=1.43.7; version=1.44.4; version=1.45.2

Published CVSS scores

6.9Wikimedia FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA: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.

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

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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