CVE-2026-46644

Description

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.

References

https://github.com/symfony/polyfill/security/advisories/GHSA-2xf4-cg6j-vhgq

https://github.com/symfony/polyfill/releases/tag/v1.38.1

https://github.com/symfony/polyfill/commit/1be936e2491ccebe152bd736dfc91eb1422c8bec

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS