BlackTreeCVE Intelligence
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Full vulnerability report · 2026
CVE-2026-33667High confidence

OpenProject: 2FA OTP Verification Missing Rate Limiting

opf · openproject

Official source article: GitHub GHSA-234R-45M2-W6CV ↗. Check the applicable product and release in the original source.

7.4HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 15 Apr 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.40% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs opf openproject and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-23014

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

OpenProject is an open-source project management application. In versions prior to 17.3.0, 2FA OTP verification in the confirm_otp action of the two_factor_authentication module has no rate limiting, lockout mechanism, or failed-attempt tracking. The existing brute_force_block_after_failed_logins setting only counts password login failures and does not apply to the 2FA verification stage, and neither the fail_login nor stage_failure methods increment any counter, lock the account, or add any delay. With the default TOTP drift window of ±60 seconds allowing approximately 5 valid codes at any time, an attacker who knows a user's password can brute-force the 6-digit TOTP code at roughly 5-10 attempts per second with an expected completion time of approximately 11 hours. The same vulnerability applies to backup code verification. This effectively allows complete 2FA bypass for any account where the password is known. This issue has been fixed in version 17.3.0.

What

OpenProject is an open-source project management application. In versions prior to 17.3.0, 2FA OTP verification in the confirm_otp action of the two_factor_authentication module has no rate limiting, lockout mechanism, or failed-attempt tracking. The existing brute_force_block_after_failed_logins setting only counts password login failures and does not apply to the 2FA verification stage, and neither the fail_login nor stage_failure methods increment any counter, lock the account, or add any delay. With the default TOTP drift window of ±60 seconds allowing approximately 5 valid codes at any time, an attacker who knows a user's password can brute-force the 6-digit TOTP code at roughly 5-10 attempts per second with an expected completion time of approximately 11 hours. The same vulnerability applies to backup code verification. This effectively allows complete 2FA bypass for any account where the password is known. This issue has been fixed in version 17.3.0.

Why

The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

OpenProject is an open-source project management application. In versions prior to 17.3.0, 2FA OTP verification in the confirm_otp action of the two_factor_authentication module has no rate limiting, lockout mechanism, or failed-attempt tracking. The existing brute_force_block_after_failed_logins setting only counts password login failures and does not apply to the 2FA verification stage, and neither the fail_login nor stage_failure methods increment any counter, lock the account, or add any delay. With the default TOTP drift window of ±60 seconds allowing approximately 5 valid codes at any time, an attacker who knows a user's password can brute-force the 6-digit TOTP code at roughly 5-10 attempts per second with an expected completion time of approximately 11 hours. The same vulnerability applies to backup code verification. This effectively allows complete 2FA bypass for any account where the password is known. This issue has been fixed in version 17.3.0.

Why

The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Restriction of Excessive Authentication Attempts → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-307 ↗

CWE-307: Improper Restriction of Excessive Authentication Attempts. The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-307Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20260422Security Bulletin 22 April 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 22 April 2026, published on 22 April 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-013182OpenProjectにおける過度な認証試行の不適切な制限に関する脆弱性

OpenProjectはオープンソースのプロジェクト管理アプリケーションです。バージョン17.3.0より前のバージョンでは、two_factor_authenticationモジュールのconfirm_otpアクションにおける2FAのOTP検証に対してレート制限やロックアウト機構、失敗試行の追跡がありませんでした。既存のbrute_force_block_after_failed_logins設定はパスワードログインの失敗のみをカウントしており、2FA検証段階には適用されず、fail_loginやstage_failureメソッドもカウンターを増加させたり、アカウントをロックしたり、遅延を追加したりしませんでした。±60秒のデフォルトTOTPドリフトウィンドウにより常時約5個の有効なコードが存在するため、攻撃者がユーザーのパスワードを知っている場合、6桁のTOTPコードを毎秒約5回から10回の試行速度でブルートフォース攻撃でき、完了までの期待時間は約11時間となります。同様の脆弱性はバックアップコードの検証にも影響します。これによりパスワードが既知の任意のアカウントに対して、実質的に完全な2FAの回避が可能となります。この問題はバージョン17.3.0で修正されました。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
openproject: < 17.3.0
Fixed
17.3.0.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 15 Apr 2026 · Last source change 15 Apr 2026, 20:00 UTC · CWE-307 · Improper Restriction of Excessive Authentication Attempts

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-23014
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-33667 · cve.blacktree.nl