CVE-2026-91971Network attack vectorHinoki check available

Authenticated service crash via unlimited image decoding

Published Sep 15, 2026 · Updated Sep 15, 2026

Resource exhaustion in Vikunja before 2.6.0 allows remote authenticated users to crash the service through crafted image uploads. The avatar and project-background upload handlers decode and resize images without limiting decoded pixel counts, so tiny PNG files with extreme aspect ratios expand to roughly two billion pixels. Any authenticated account can repeat or parallelize uploads to consume CPU and memory until the process is killed, interrupting the self-hosted instance until it restarts.

CVSS severityUnavailable
Unscored
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource exhaustion in Vikunja before 2.6.0 allows remote authenticated users to crash the service through crafted image uploads. The avatar and project-background upload handlers decode and resize images without limiting decoded pixel counts, so tiny PNG files with extreme aspect ratios expand to roughly two billion pixels. Any authenticated account can repeat or parallelize uploads to consume CPU and memory until the process is killed, interrupting the self-hosted instance until it restarts.

The record

CVE
CVE-2026-91971
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
Vikunja
Product
Vikunja
Classifications
T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 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=0 <2.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Vikunja · Vikunjaversion=0 <2.6.0

Published CVSS scores

No CVSS assessment is available in this record.

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

Weakness, pattern, technique

T1499.004Application or System Exploitation

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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