GHSA-529g-xq4f-cw38
MEDIUMGHSA-529g-xq4f-cw38 is a medium-severity (CVSS 5.3) Server-Side Request Forgery (SSRF) vulnerability in @astrojs/netlify. O3 Security confirms whether GHSA-529g-xq4f-cw38 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
@astrojs/netlify broadens Astro image.remotePatterns in Netlify Image CDN config
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 GHSA-529g-xq4f-cw38.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-529g-xq4f-cw38 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 372,324 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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.
@astrojs/netlifynpmDescription
Summary
@astrojs/netlify converts Astro image.remotePatterns into Netlify Image CDN images.remote_images regular expressions with broader semantics than Astro's canonical matcher. A single wildcard hostname such as *.example.com is converted to an optional subdomain regex, so the apex host matches. A single wildcard pathname such as /ok/* is converted without end anchoring, so deeper paths match by prefix.
Technical details
The Netlify adapter generates regex strings for Netlify Image CDN from image.remotePatterns. For *.example.com, it emits ([a-z0-9-]+\\.)?example\\.com, which makes the subdomain optional. Astro's canonical helper requires exactly one subdomain and rejects the apex host.
For /ok/*, the adapter emits a segment regex but does not anchor the end of the URL. Netlify's Image CDN implementation treats images.remote_images entries as JavaScript regular expressions and calls .test(sourceImageUrl.href), so a URL such as /ok/a/b.svg matches the /ok/a prefix even though Astro's helper rejects it.
The latest npm package @astrojs/[email protected] contains this conversion logic, and a minimal Astro build writes the broadened patterns into .netlify/v1/config.json.
Reproduction
- Create an Astro app using
[email protected]and@astrojs/[email protected]. - Configure Netlify output and a restrictive image pattern, for example
remotePatterns: [{ protocol: 'http', hostname: '*.localhost', pathname: '/ok/*' }]. - Build the app and observe that
.netlify/v1/config.jsoncontainshttp://([a-z0-9-]+\\.)?localhost(:[0-9]+)?(\\/ok/[^/?#]+)/?([?][^#]*)?. - Serve a canary SVG on
127.0.0.1:9001. - Request
/.netlify/images?url=http%3A%2F%2Flocalhost%3A9001%2Fok%2Fa.svg&w=100. Astro's helper rejects the apexlocalhostfor*.localhost, but Netlify Image CDN accepts it and fetches the canary. - As a negative control, request
/.netlify/images?url=http%3A%2F%2Flocalhost%3A9001%2Fnope%2Fa.svg&w=100. This returns403 Forbidden: Remote image URL not allowedand does not hit the canary. - Request
/.netlify/images?url=http%3A%2F%2Flocalhost%3A9001%2Fok%2Fa%2Fb.svg&w=100. Astro's/ok/*helper rejects this deeper path, but Netlify Image CDN accepts it and fetches the canary.
Impact
Any Astro app deployed with @astrojs/netlify and a restrictive image.remotePatterns config can expose a wider image-fetch boundary than intended. Public requests to the Netlify Image CDN endpoint can fetch URLs that Astro's own matcher would reject, including apex hosts for *.host patterns and deeper paths for /path/* patterns. The practical impact depends on what the application intended to isolate behind the remote image allowlist, but it can disclose image-like resources from unintended hosts or paths behind the same configured remote origin family.
Remediation
Generate regexes that exactly match Astro's canonical matchHostname and matchPathname semantics, and anchor the full URL match before writing images.remote_images. In particular, *.example.com should require exactly one subdomain and should not match example.com, and /ok/* should match exactly one additional path segment and should not match /ok/a/b.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @astrojs/netlify | all versions | 7.0.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @astrojs/netlify. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @astrojs/netlify to 7.0.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-529g-xq4f-cw38 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.
How O3 protects you
O3 pinpoints whether GHSA-529g-xq4f-cw38 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-529g-xq4f-cw38. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-529g-xq4f-cw38 in your dependencies?
O3 detects GHSA-529g-xq4f-cw38 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.