CVE-2026-46644

Summary

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.

Affected Software

VendorProductVersion RangeStatus
symfonypolyfill>= 1.17.1, < 1.38.1affected
symfonypolyfill-intl-idn>= 1.17.1, < 1.38.1affected

Weaknesses

  • CWE-1289: CWE-1289: Improper Validation of Unsafe Equivalence in Input

References