Medium 6.9Published Jul 14, 2026

CVE-2026-46644symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence

Updated under an hour ago (Oct 26, 2026, 6:30 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for symfony polyfill

Exploited in the last 30 days

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.

CVSS: 6.9 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
Weakness (CWE): CWE-1289
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Awaiting Analysis
Record last updated: Jul 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

symfony polyfill symfony:polyfill (from the name)	from 1.17.1, < 1.38.1	CNA record
symfony polyfill-intl-idn symfony:polyfill_intl_idn (from the name)	from 1.17.1, < 1.38.1	CNA record

References

References

https://github.com/symfony/polyfill/security/advisories/GHSA-2xf4-cg6j-vhgq	x-refsource-confirm
https://github.com/symfony/polyfill/commit/1be936e2491ccebe152bd736dfc91eb1422c8bec	x-refsource-misc
https://github.com/symfony/polyfill/releases/tag/v1.38.1	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.