Riskcovery

CVE-2026-46644

symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence

State
Published
Severity
6.9 Medium
Published
Jul 14, 2026
Updated
Jul 15, 2026
Reserved
May 15, 2026

Read the record on cve.org

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.

Scores

CVSSScoreVectorSource
4.06.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:NGitHub_M

Weaknesses

  • CWE-1289 Improper Validation of Unsafe Equivalence in Input

Affected Products

ProductVersions
polyfillsymfony
  • >= 1.17.1, < 1.38.1Affected
polyfill-intl-idnsymfony
  • >= 1.17.1, < 1.38.1Affected

References

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