Security Advisory: Astro Vercel Adapter Path Override Bypass (CVE-2026-33768)
We proactively patched a medium-severity vulnerability in the Astro Vercel adapter that could allow path override bypass on server-rendered routes. No evidence of exploitation was found.
On March 29, 2026, we patched a medium-severity vulnerability (CVSS 6.5) in our web infrastructure. This advisory provides transparency about the issue, our response, and what it means for your data.
What Happened
The Astro project disclosed CVE-2026-33768, a path override bypass vulnerability in the @astrojs/vercel adapter. The vulnerability allowed crafted requests to manipulate server-side routing via the x-astro-path header or query parameter, potentially bypassing route-level access controls on server-rendered pages.
Were Skillsmith Users Affected?
No evidence of exploitation was found. We reviewed server logs and access patterns prior to patching and observed no suspicious activity targeting this vector.
However, because Skillsmith uses server-rendered (SSR) routes for authenticated pages — including login, account management, and billing — we treated this as a high-urgency fix despite the medium CVSS score.
What We Did
We applied the patch within hours of the upstream disclosure:
- Upgraded
@astrojs/vercelfrom 9.0.3 to 9.0.5, which backports the security fix for Astro 5 compatibility - Validated the fix across all server-rendered routes, including authentication flows and dynamic pages
- Hardened CI workflows with explicit permission scoping (a separate CodeQL finding addressed in the same batch)
The fix required no changes to application code or configuration — only a dependency version bump.
What You Need to Do
Nothing. The patch is deployed to production. No action is required from Skillsmith users. Your API keys, account data, and skill configurations were not exposed.
Timeline
| Time | Event |
|---|---|
| March 29, 2026 | Upstream advisory published (GHSA-mr6q-rp88-fx84) |
| March 29, 2026 | Skillsmith team identifies affected routes and assesses risk |
| March 29, 2026 | Patch applied, tested, and merged (PR #402) |
| March 29, 2026 | Deployed to production via Vercel |
Technical Details
The vulnerability existed in the Vercel adapter’s request routing layer. Astro’s server-side rendering uses internal headers to coordinate routing between the edge and serverless functions. CVE-2026-33768 allowed external requests to inject these internal routing signals, potentially redirecting server-side processing to unintended routes.
Our deployment uses SSR for 13+ routes (authentication, account management, pricing, and dynamic skill pages), with middleware-based A/B routing that exercises the same path manipulation surface. The @astrojs/[email protected] release patches this by validating and sanitizing routing inputs before they reach the application layer.
Our Commitment
Security is foundational to Skillsmith. When you install skills through our platform, you trust us to protect your development environment. We take that seriously — from the multi-layered skill security scanner that protects against malicious skills, to proactive infrastructure patching like this advisory.
If you have questions about this advisory, contact us at [email protected].
References:
- GHSA-mr6q-rp88-fx84 — Upstream advisory
- Skillsmith Security Policy — Vulnerability reporting and disclosure process