CVE-2025-61925 is a medium-severity (CVSS 6.5) CWE-470 vulnerability in astro. A fix is available for astro — see the affected versions and patch details below.
Astro's `X-Forwarded-Host` is reflected without validation
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-61925.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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.
astronpmDescription
Summary
When running Astro in on-demand rendering mode using a adapter such as the node adapter it is possible to maliciously send an X-Forwarded-Host header that is reflected when using the recommended Astro.url property as there is no validation that the value is safe.
Details
Astro reflects the value in X-Forwarded-Host in output when using Astro.url without any validation.
It is common for web servers such as nginx to route requests via the Host header, and forward on other request headers. As such as malicious request can be sent with both a Host header and an X-Forwarded-Host header where the values do not match and the X-Forwarded-Host header is malicious. Astro will then return the malicious value.
This could result in any usages of the Astro.url value in code being manipulated by a request. For example if a user follows guidance and uses Astro.url for a canonical link the canonical link can be manipulated to another site. It is not impossible to imagine that the value could also be used as a login/registration or other form URL as well, resulting in potential redirecting of login credentials to a malicious party.
As this is a per-request attack vector the surface area would only be to the malicious user until one considers that having a caching proxy is a common setup, in which case any page which is cached could persist the malicious value for subsequent users.
Many other frameworks have an allowlist of domains to validate against, or do not have a case where the headers are reflected to avoid such issues.
PoC
- Check out the minimal Astro example found here: https://github.com/Chisnet/minimal_dynamic_astro_server
nvm useyarn run buildnode ./dist/server/entry.mjscurl --location 'http://localhost:4321/' --header 'X-Forwarded-Host: www.evil.com' --header 'Host: www.example.com'- Observe that the response reflects the malicious
X-Forwarded-Hostheader
For the more advanced / dangerous attack vector deploy the application behind a caching proxy, e.g. Cloudflare, set a non-zero cache time, perform the above curl request a few times to establish a cache, then perform the request without the malicious headers and observe that the malicious data is persisted.
Impact
This could affect anyone using Astro in an on-demand/dynamic rendering mode behind a caching proxy.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | astro | all versions | 5.14.3npm install astro@5.14.3 |
Affected Products
astroastroDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for astro, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update astro to 5.14.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-61925 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Frequently Asked Questions
Is CVE-2025-61925 in your dependencies?
Find it across npm, including transitive dependencies.