Symfony Polyfill up to 1.38.0 Intl IDN process server-side request forgery

Summaryinfo

A vulnerability was found in Symfony Polyfill up to 1.38.0. It has been rated as critical. This affects the function process of the component Intl IDN. This manipulation causes server-side request forgery. This vulnerability is tracked as CVE-2026-46644. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in Symfony Polyfill up to 1.38.0 and classified as critical. Affected by this vulnerability is the function process of the component Intl IDN. The manipulation with an unknown input leads to a server-side request forgery vulnerability. The CWE definition for the vulnerability is CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Symfony Polyfill backports PHP features and provides compatibility layers for extensions and functions. From 1.17.1 until 1.38.1, symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload is empty or decodes to ASCII-only code points because Idn::process() does not enforce the UTS #46 revision 33 requirement that decoded ACE labels contain at least one non-ASCII code point. Originally unequal domain names can be regarded as equal, which can lead to blacklist bypassing, inconsistent URL parsing, and server-side request forgery in applications using the polyfill to canonicalise or compare hostnames. This issue is fixed in version 1.38.1.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-46644 since 05/15/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

Upgrading to version 1.38.1 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• Symfony

Name

• Polyfill

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38.0

License

• open-source

Website

• Product: https://github.com/symfony/polyfill/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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