Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:NSummary
CVE-2026-23625 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Openproject Openproject. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 11th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
OpenProject, an open-source web-based project management software, is affected by CVE-2026-23625, a stored cross-site scripting (XSS) vulnerability (CWE-79) in its Roadmap view, impacting versions 16.3.0 through 16.6.4. The vulnerability arises when the Roadmap view renders the "Related work packages" list for a version that includes work packages from a different project, such as a subproject. The helper method link_to_work_package prepends the project name (package.project.to_s) to the link and marks the output as .html_safe without escaping. Since project names are user-controlled, any HTML injected into a subproject name is rendered verbatim in the page. The issue stems from a refactoring to Rails standard content-security policy in version 16.3.0, which inadvertently removed the X-Content-Type-Options: nosniff header.
An authenticated attacker with low privileges (PR:L) can exploit this vulnerability over the network (AV:N) with low complexity (AC:L) by creating or controlling a subproject with a malicious HTML payload in its name. The attack requires user interaction (UI:R) from a victim viewing the affected Roadmap view, but achieves cross-origin scope change (S:C), enabling high confidentiality (C:H) and integrity (I:H) impacts with no availability disruption (A:N), as scored at CVSS 8.7. Successful exploitation allows the injected script to execute in the context of other users' browsers, potentially leading to session hijacking, data theft, or page manipulation.
Mitigation is provided in OpenProject versions 16.6.5 and 17.0.0, which restore the X-Content-Type-Options: nosniff header. Organizations unable to upgrade should configure their proxying web application server to add this header. Additional details are available in the OpenProject security advisory (GHSA-cvpq-cc56-gwxx) and release notes for versions 16.6.5 and 17.0.0.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-3309
Vulnerability Data
OpenProject is an open-source, web-based project management software. Versions 16.3.0 through 16.6.4 are affected by a stored cross-site scripting vulnerability in the Roadmap view. OpenProject’s roadmap view renders the “Related work packages” list for each version. When a version contains…
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work packages from a different project (e.g., a subproject), the helper link_to_work_package prepends package.project.to_s to the link and returns the entire string with .html_safe. Because project names are user-controlled and no escaping happens before calling html_safe, any HTML placed in a subproject name is injected verbatim into the page. The underlying issue is mitigated in versions 16.6.5 and 17.0.0 by setting a `X-Content-Type-Options: nosniff` header, which was in place until a refactoring move to Rails standard content-security policy, which did not properly apply this header in the new configuration since OpenProject 16.3.0. Those who cannot upgrade their installations should ensure that they add a X-Content-Type-Options: nosniff header in their proxying web application server.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.1.2V1.3.2
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect input neutralization through targeted web-application tests.
Input validation directly enforces neutralization of untrusted data before it reaches web output generation.
Output filtering can catch or sanitize unneutralized script content before it is served to users.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).
Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure-coding testing and automated code-analysis tools are applied to detect improper neutralization of script-related content during web-page generation.
Knowledge exchange on emerging attack techniques and patches reduces the likelihood that cross-site scripting flaws remain unaddressed in deployed applications.
Operational indicators of compromise for web-application attacks can be incorporated into WAF or input-filtering rules, lowering the likelihood that unsanitized data reaches the browser.
Requiring language-specific secure-coding standards and automated scanning during the SDLC catches missing output encoding or improper neutralization of untrusted data before the software reaches production.
Secure-coding standards, SAST scans and removal of insecure code samples together eliminate the failure to neutralize script content that produces cross-site scripting flaws.
Webpage malware scanning and block-listing of known malicious sites reduce the likelihood that reflected or stored script payloads reach a user’s browser.