2FA bypass via client-supplied WebAuthn challenge
Published Mar 6, 2026 · Updated Mar 6, 2026
Authentication bypass in OneUptime 10.0.11 and earlier allows remote authenticated users to access victim accounts by replaying WebAuthn assertions. The login verification path reads expectedChallenge from the request body and passes it to verifyAuthenticationResponse instead of comparing it with server-stored state. Exploitation requires the victim's password and a captured valid assertion; successful replay returns a session token with the victim's account access.
Summary
What happened
Authentication bypass in OneUptime 10.0.11 and earlier allows remote authenticated users to access victim accounts by replaying WebAuthn assertions. The login verification path reads expectedChallenge from the request body and passes it to verifyAuthenticationResponse instead of comparing it with server-stored state. Exploitation requires the victim's password and a captured valid assertion; successful replay returns a session token with the victim's account access.
The record
- CVE
- CVE-2026-28787
- Published
- Mar 6, 2026
- Updated
- Mar 6, 2026
- Vendor
- OneUptime
- Product
- OneUptime
- Classifications
- CWE-287, CWE-294, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 6, 2026CVE publishedPublication date reported by the CVE source.
- Mar 6, 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.
- Affected versionversion=<= 10.0.11
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- GHSA-gjjc-pcwp-c74m WebAuthn assertion replay proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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