CVE-2026-80199Public exploitNetwork attack vectorHinoki check available

Username enumeration via legacy API timing oracle

Published Aug 25, 2026 · Updated Aug 25, 2026

Information disclosure in Kimai before 2.54.0 allows remote attackers to enumerate valid usernames through legacy API headers. TokenAuthenticator hashes a supplied password only after finding the X-AUTH-USER value, so nonexistent users receive measurably faster responses. No authentication is required, but repeated timing samples reveal only account validity; response bodies and status codes remain identical.

CVSS severity6.3
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Information disclosure in Kimai before 2.54.0 allows remote attackers to enumerate valid usernames through legacy API headers. TokenAuthenticator hashes a supplied password only after finding the X-AUTH-USER value, so nonexistent users receive measurably faster responses. No authentication is required, but repeated timing samples reveal only account validity; response bodies and status codes remain identical.

The record

CVE
CVE-2026-80199
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Kimai
Product
Kimai
Classifications
CWE-208, T1087
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 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=0 <2.54.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Kimai · Kimaiversion=0 <2.54.0

Published CVSS scores

3.7VulnCheck CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
6.3VulnCheck CNACVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

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 exploitPublished

Weakness, pattern, technique

CWE-208Observable Timing Discrepancy
T1087Account Discovery

Public exploit references

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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