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CVSS estimates technical severity, but it does not automatically equal business risk. Prioritize using context like internet exposure, asset criticality, known exploitation, and whether compensating controls exist. A Medium CVSS on an exposed production system can be more urgent than a Critical on an isolated non-production host.

Vulnerability Database

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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

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A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. Risk increases sharply when exploitation becomes reliable or widespread.

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Recurring findings usually come from incomplete asset discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host.

Q: How do we prioritize remediation without burning out the team?

Use a repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress so remediation is steady, not reactive.

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362,557

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@astrojs/netlify generates an overly-broad Netlify Image CDN allowlist because remotePatterns.pathname metacharacters are not escaped — @astrojs / netlify

Incorrect Regular Expression

Summary

The @astrojs/netlify adapter converts each image.remotePatterns entry into a regular expression that is written to .netlify/v1/config.json under images.remote_images. Netlify's Image CDN uses these regexes as the allowlist that decides which remote image URLs it will optimize. remotePatternToRegex() escapes . in the hostname but interpolates the literal pathname into the regex without escaping regex metacharacters. As a result, the generated allowlist is broader than the pattern the developer declared, and broader than Astro's canonical matchPattern() helper (which compares non-wildcard pathnames by exact string equality).

This is a residual of the same bug class addressed in CVE-2026-54300 (PR #17018, commit 1310277d). That fix corrected wildcard semantics and added a $ anchor but did not add metacharacter escaping for literal pathnames.

Details

In packages/integrations/netlify/src/index.ts, remotePatternToRegex() escapes dots in the hostname:

regexStr += hostname.replace(/\./g, &#039;\\.&#039;);

but interpolates the pathname unescaped in all three branches, e.g. the exact-match branch:

regexStr += `(\\${pathname})`;

Any regex metacharacter in the literal path (., +, ?, (, [, ...) is therefore passed through raw. Because . matches any character (including /), a restrictive pattern is silently widened.

The security boundary on Netlify is the generated regex itself — Netlify's Image CDN enforces it directly and Astro's runtime matchPattern() is not in the loop for this path, so there is no compensating layer that re-validates the request.

Proof of Concept

Configure an SSR site with a literal pathname containing a .:

// astro.config.mjs
image: {
  remotePatterns: [{
    protocol: &#039;https&#039;,
    hostname: &#039;cdn.example.com&#039;,
    pathname: &#039;/img/v1.0/file&#039;,
  }],
}

Run astro build and inspect .netlify/v1/config.json images.remote_images[0]:

https://cdn\.example\.com(:[0-9]+)?(\/img/v1.0/file)([?][^#]*)?$

Testing the generated regex:

https://cdn.example.com/img/v1.0/file -> MATCH (intended)
https://cdn.example.com/img/v1X0/file -> MATCH (bypass; the unescaped . matches any character)
https://cdn.example.com/img/v1/0/file -> MATCH (bypass; . also matches /, crossing a path segment)

Astro's canonical matchPattern() (exact string equality on the pathname) rejects both bypass URLs.

Impact

Netlify's Image CDN accepts optimization requests for URLs on the allowed host that the developer's remotePatterns entry was intended to exclude. The hostname remains correctly anchored, so the broadening is confined to the pathname dimension on an already-allowed host. Realistic impact depends on whether other images the developer meant to keep out of their CDN exist at metacharacter-adjacent paths on that host. This affects reasonable, non-permissive configurations, since any pathname containing a . (file extensions, version segments) is affected.

Patches

A fix will escape all regex metacharacters in the literal portions of each remotePatterns component before interpolation, applying only Astro's documented wildcard semantics explicitly. A regression corpus validates the generated Netlify regexes against @astrojs/internal-helpers' matchPattern().

Workarounds

Avoid regex metacharacters (notably .) in image.remotePatterns[].pathname values, or scope the allowed host so that unintended paths are not reachable.

Credit

Reported by @sec-reex as part of an incomplete-patch measurement study (responsible disclosure).

Published: Jul 20, 2026
Updated: Jul 21, 2026
GHSA: GHSA-hp3v-mfqw-h74c
Severity: Low
Exploit:
CISA KEV:

CVSS v3:

Severity: Low
Score: 3.7
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CWEs:

CWE-185

Affected Software
References

Software	From	Fixed in
@astrojs / netlify	-	8.1.2

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Frequently Asked Questions

What is a Vulnerability (CVE) and why does it matter?

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.