VulnerabilityPublished 10 Jan 2026Updated 13 Jan 2026

CVE-2026-22603: opf openproject · Improper Restriction of Excessive Authentication Attempts

Affects opf openprojectSource CVE Database V5

Not known to be exploited · CVSS 6.9 Medium : upgrade to 16.6.2 when convenient.

Data as of 26 Oct 2026, 09:16 UTC

CVSS 4.0 base score

6.9Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 16.6.2

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade openproject and opf/openproject to 16.6.2.

Affected software

Product	Affected	Fixed in
opfopenproject	Affected <16.6.2	Fixed in 16.6.2
GitHubopf/openproject`pkg:github/opf/openproject`Other threats	Affected <16.6.2	Fixed in 16.6.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations using OpenProject should immediately upgrade to version 16.6.2 or later, where the vulnerability is patched. If upgrading is not feasible, applying the vendor-provided manual patch to secure the password-change endpoint is critical. Organizations should implement additional compensating controls such as web application firewalls (WAFs) to detect and block abnormal password-change request patterns and rate-limit requests at the network perimeter. Enforcing strong password policies and encouraging users to adopt multi-factor authentication (MFA) where supported can reduce the risk of successful password guessing. Monitoring logs for unusual password-change activity and failed attempts can help detect ongoing attacks. Restricting access to the OpenProject instance via IP whitelisting or VPNs can further reduce exposure. Regular security assessments and penetration testing focused on authentication mechanisms are recommended to identify similar weaknesses. Finally, educating users about the risks of weak passwords and phishing can help mitigate account compromise risks.

Description

OpenProject is an open-source, web-based project management software. Prior to version 16.6.2, OpenProject’s unauthenticated password-change endpoint (/account/change_password) was not protected by the same brute-force safeguards that apply to the normal login form. In affected versions, an attacker who can guess or enumerate user IDs can send unlimited password-change requests for a given account without triggering lockout or other rate-limiting controls. This allows automated password-guessing (e.g., with wordlists of common passwords) against valid accounts. Successful guessing results in full account compromise for the targeted user and, depending on that user’s role, can lead to further privilege escalation inside the application. This issue has been patched in version 16.6.2. Those who are unable to upgrade may apply the patch manually.

Impact

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of project management data and user accounts. Compromise of user accounts, especially those with administrative or elevated privileges, can lead to unauthorized access to sensitive project information, manipulation of project data, and disruption of workflows. This can affect organizations relying on OpenProject for collaboration, planning, and resource management, including government agencies, engineering firms, and software development companies. The lack of brute-force protections on the password-change endpoint increases the likelihood of automated attacks, potentially leading to widespread account compromises if user IDs are easily enumerable. Additionally, compromised accounts may be leveraged for lateral movement or privilege escalation within the organization’s IT environment. The vulnerability could also undermine trust in project management processes and lead to compliance issues under data protection regulations such as GDPR if personal or sensitive data is exposed or altered.

CWE-307Improper Restriction of Excessive Authentication Attempts (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product does not implement sufficient measures to prevent multiple failed authentication attempts within a short time frame.
Architecture and Design
Common protection mechanisms include: Disconnecting the user after a small number of failed attempts; Implementing a timeout; Locking out a targeted account; Requiring a computational task on the user's part.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
Authentication (opens in a new tab)
Transport Layer Protection (opens in a new tab)
TLS Cipher String (opens in a new tab)
OWASP ASVS 4.0.3
V2.2.1 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
Attack patterns
Dictionary-based Password Attack (opens in a new tab)
Password Brute Forcing (opens in a new tab)
Password Spraying (opens in a new tab)
Credential Stuffing (opens in a new tab)
Use of Known Kerberos Credentials (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Jan 2026, 07:43 UTC

WeaknessesCWE-307

Technical details

References

Community reviews

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