Astro: Unauthenticated path override in the @astrojs/vercel ISR function

published 2026-07-20 3 mo ago modified 2026-10-23 17 d ago also EUVD-2026-60306 , GHSA-x27w-589x-frm2

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits: 0; none known

Astro is a web framework for content-driven websites. From 10.0.3 until 11.0.3, the Astro Vercel adapter in packages/integrations/vercel/src/serverless/entrypoint.ts accepts x_astro_path for the public /_isr function based only on the x-vercel-isr header, allowing unauthenticated GET requests to render routes protected only by Vercel edge path rules or split edge middleware. This issue is fixed in 11.0.3.

Patch / fix

fixed in 2 links 5

npm @astrojs/vercel 11.0.3
astro @astrojs/vercel 11.0.3

github.com/withastro/astro@3a43cf0 commit
github.com/withastro/astro@aa26636 commit
github.com/withastro/astro#17370 pull request
github.com/withastro/astro#16079 pull request
github.com/withastro/astro/releases/tag/@astrojs/vercel@11.0.3 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 2 mo ago (2026-08-18)

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/withastro/astro/security/advisories/GHSA-x27w-589x-frm2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
npm	@astrojs/vercel	>=10.0.3, <11.0.3	11.0.3

Affected products

withastro astro

Classification

Weakness

CWE-441 Unintended Proxy or Intermediary
CWE-862 Missing Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary