GHSA-hqr9-c56f-3x7f is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in @angular/platform-server. A fix is available for @angular/platform-server — see the affected versions and patch details below.
@angular/platform-server: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-hqr9-c56f-3x7f.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-hqr9-c56f-3x7f by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@angular/platform-servernpmDescription
A Cross-Site Scripting (XSS) vulnerability exists in @angular/platform-server's DOM emulation dependency (domino) when serializing the content of raw-text elements (such as <script>, <style>, and <iframe>).
domino supports escaping raw-text elements during serialization to prevent closing-tag breakout. However, a Unicode index alignment bug existed in this escaping logic.
In JavaScript, string lengths and character indices are calculated based on UTF-16 code units (where astral characters—such as emojis—occupy 2 code units / 4 bytes). If the bound dynamic text contained astral Unicode characters before the closing tag (e.g. </script>, </style>, or </iframe>), the index offset calculation in domino's replacement logic shifted.
This misalignment caused domino to fail to replace or escape the closing tag, leaving it raw and unescaped in the output HTML.
An attacker who controls the dynamic text can supply a payload containing both an astral Unicode character and a closing tag (e.g., 😀</iframe><script>alert(1)</script>). When serialized on the server during SSR, the browser parses the unescaped closing tag, exits the raw-text context early, and executes the subsequent <script> block, leading to same-origin Cross-Site Scripting (XSS).
Impact
This vulnerability allows an attacker to perform same-origin Cross-Site Scripting (XSS) attacks against any user visiting an SSR-rendered page that binds user-controlled data inside raw-text elements. This can lead to session hijacking, credentials theft, unauthorized actions on behalf of users, and defacement.
Patched Versions
- 22.0.0-rc.2
- 21.2.16
- 20.3.24
- 19.2.25
Workarounds
If you cannot immediately update your dependencies, you can:
- Avoid binding user-controlled values inside
<iframe>or other raw-text elements. - Sanitize any user input placed inside raw-text elements to explicitly strip closing tags before passing it to the template.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @angular/platform-server | ≥ 22.0.0-next.0&&< 22.0.0-rc.2 | 22.0.0-rc.2npm install @angular/platform-server@22.0.0-rc.2 |
| 📦npm | @angular/platform-server | ≥ 21.0.0-next.0&&< 21.2.16 | 21.2.16npm install @angular/platform-server@21.2.16 |
| 📦npm | @angular/platform-server | ≥ 20.0.0-next.0&&< 20.3.24 | 20.3.24npm install @angular/platform-server@20.3.24 |
| 📦npm | @angular/platform-server | ≥ 19.0.0-next.0&&< 19.2.25 | 19.2.25npm install @angular/platform-server@19.2.25 |
| 📦npm | @angular/platform-server | all versions | No fix |
Affected Products
angularangularDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @angular/platform-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @angular/platform-server to 22.0.0-rc.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-hqr9-c56f-3x7f is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is GHSA-hqr9-c56f-3x7f in your dependencies?
Find it across npm, including transitive dependencies.