CVE-2026-33667Public exploitNetwork attack vector

Account takeover via unthrottled 2FA code guessing

Published Apr 15, 2026 · Updated Apr 15, 2026

Authentication bypass in OpenProject before 17.3.0 allows remote authenticated users to access accounts by brute-forcing 2FA codes. The confirm_otp action passes failed TOTP and backup-code checks through fail_login and stage_failure without incrementing a counter, locking the account, or delaying retries. A valid password is required, after which repeated six-digit code guesses defeat the second factor and grant access as the target account.

CVSS severity7.4
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in OpenProject before 17.3.0 allows remote authenticated users to access accounts by brute-forcing 2FA codes. The confirm_otp action passes failed TOTP and backup-code checks through fail_login and stage_failure without incrementing a counter, locking the account, or delaying retries. A valid password is required, after which repeated six-digit code guesses defeat the second factor and grant access as the target account.

The record

CVE
CVE-2026-33667
Published
Apr 15, 2026
Updated
Apr 15, 2026
Vendor
OpenProject GmbH
Product
OpenProject
Classifications
CWE-307, T1110
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 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=< 17.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenProject GmbH · OpenProjectversion=< 17.3.0

Published CVSS scores

7.4GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A: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.

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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 exploitPublished

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
T1110Brute Force

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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