Kimai
CVE-2026-80199
MEDIUM
Severity by source
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-reachable, no privileges needed; AC:H reflects timing-attack noise requiring statistical sampling; impact is solely low confidentiality (username enumeration only).
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
2DescriptionCVE.org
Kimai before 2.54.0 contains a timing oracle vulnerability in TokenAuthenticator that allows unauthenticated attackers to enumerate valid usernames via X-AUTH-USER header. Attackers can measure response time differences when the password hasher runs only for existing users, enabling username enumeration with no login throttling protection.
AnalysisAI
Timing oracle in Kimai's TokenAuthenticator (all 2.x versions before 2.54.0) allows unauthenticated network attackers to enumerate valid usernames by measuring a consistent ~25ms response time differential - argon2id password hashing executes only when a matched user record exists, leaking username validity despite identical HTTP 403 response bodies. No authentication, API token, or session cookie is required to exploit this flaw against default Kimai deployments. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attack requires network access to the Kimai API (`/api/*` endpoints) and the presence of Kimai 2.x with legacy `X-AUTH-USER` / `X-AUTH-TOKEN` header authentication enabled - which is the default configuration in the 2.x series. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 vector (AV:N/AC:H/AT:P/PR:N/UI:N/VC:L) correctly characterizes this as a network-reachable, no-privilege-required flaw with low confidentiality impact - the score of 6.3 is appropriate. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An unauthenticated attacker with network access to a Kimai instance sends repeated requests to `/api/users/me` with candidate usernames in the `X-AUTH-USER` header and a dummy `X-AUTH-TOKEN`, measuring median response latency across 15 or more probes per candidate. Usernames that consistently return responses ~25ms slower than a known-invalid baseline are flagged as valid accounts. … |
| Remediation | Upgrade Kimai to version 2.54.0 or later - this is the vendor-released patch confirmed in both the GitHub Security Advisory (GHSA-jrc6-fmhw-fpq2) and the Composer package metadata. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-208 – Observable Timing Discrepancy
View allSame technique Information Disclosure
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External POC / Exploit Code
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