7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2025-68616

CVE-2025-68616: WeasyPrint Vulnerable to Server-Side Request Forgery (SSRF) Protection Bypass via HTTP Redirect

WeasyPrint helps web developers to create PDF documents. Prior to version 68.0, a server-side request forgery (SSRF) protection bypass exists in WeasyPrint's default_url_fetcher. The vulnerability allows attackers to access internal network resources (such as localhost services or cloud metadata endpoints) even when a developer has implemented a custom url_fetcher to block such access. This occurs because the underlying urllib library follows HTTP redirects automatically without re-validating the new destination against the developer's security policy. Version 68.0 contains a patch for the issue.

(GitHub Advisory)

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CVE-2025-68616

CVE-2025-68616:

7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
weasyprint	pip	< 68.0	68.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability exists in WeasyPrint's default_url_fetcher function, which is responsible for fetching external resources like images or stylesheets referenced in an HTML document. The core of the issue is a Time-of-Check to Time-of-Use (TOCTOU) flaw related to how HTTP redirects are handled. Developers could use a custom url_fetcher to implement security policies, such as blocking requests to internal IP addresses. However, this check was only performed on the initial URL provided. If that URL responded with an HTTP redirect (e.g., 301, 302), the underlying fetching mechanism would automatically follow the redirect to the new location without re-subjecting the new URL to the security validation. An attacker could exploit this by crafting a URL to a server they control which passes the initial validation, and then having that server redirect the request to a sensitive internal endpoint (e.g., http://localhost:8080/admin or a cloud metadata service). The patch addresses this vulnerability by modifying the default_url_fetcher to explicitly disable redirects by passing allow_redirects=False to the URLFetcher instance it creates. This ensures that any redirect attempts are not followed, thereby closing the SSRF loophole.

Vulnerable functions

weasyprint.urls.default_url_fetcher

weasyprint/urls.py

The `default_url_fetcher` function was vulnerable to a Server-Side Request Forgery (SSRF) bypass. It used the `URLFetcher` class to fetch resources, but it did not disable HTTP redirects. This allowed an attacker to provide a URL that would pass a developer's custom validation, but which would then redirect to a blocked internal resource. The underlying library would follow the redirect without re-validating the new URL, creating a Time-of-Check to Time-of-Use (TOCTOU) vulnerability. The patch mitigates this by explicitly setting `allow_redirects=False` in the `URLFetcher` call within `default_url_fetcher`.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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