UBUNTU-CVE-2026-46644
A vulnerability exists in symfony/polyfill-intl-idn versions from 1.17.1 up to 1.38.1 where the library accepts xn-- labels with empty or ASCII-only Punycode payloads. This occurs because Idn::process() does not enforce the UTS #46 revision 33 requirement that decoded ACE labels contain at least one non-ASCII code point. This flaw can cause originally unequal domain names to be treated as equal, potentially leading to blacklist bypassing, inconsistent URL parsing, and server-side request forgery in applications relying on this polyfill for hostname canonicalization or comparison. The issue is fixed in version 1.38.1.
AI Analysis
Technical Summary
The symfony/polyfill-intl-idn component backports PHP features for internationalized domain names. Versions from 1.17.1 to 1.38.1 improperly accept xn-- labels whose Punycode payload is empty or decodes to ASCII-only characters, violating the UTS #46 revision 33 standard that requires at least one non-ASCII code point in decoded ACE labels. This can cause domain names that should be distinct to be considered equal, enabling issues such as blacklist bypass, inconsistent URL parsing, and server-side request forgery in applications using the polyfill for hostname processing. The vulnerability is resolved in version 1.38.1.
Potential Impact
Applications using affected versions of symfony/polyfill-intl-idn to canonicalize or compare hostnames may incorrectly treat distinct domain names as equal. This can lead to security issues including bypassing domain-based blacklists, inconsistent URL parsing, and server-side request forgery. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade symfony/polyfill-intl-idn to version 1.38.1 or later, where this issue is fixed. Patch status is confirmed by the vendor advisory indicating the fix in 1.38.1. No other mitigations are specified.
UBUNTU-CVE-2026-46644
Description
A vulnerability exists in symfony/polyfill-intl-idn versions from 1.17.1 up to 1.38.1 where the library accepts xn-- labels with empty or ASCII-only Punycode payloads. This occurs because Idn::process() does not enforce the UTS #46 revision 33 requirement that decoded ACE labels contain at least one non-ASCII code point. This flaw can cause originally unequal domain names to be treated as equal, potentially leading to blacklist bypassing, inconsistent URL parsing, and server-side request forgery in applications relying on this polyfill for hostname canonicalization or comparison. The issue is fixed in version 1.38.1.
CVSS v4.0
Affected software
pkg:deb/ubuntu/[email protected]?arch=source&distro=bionicpkg:deb/ubuntu/[email protected]?arch=source&distro=jammypkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The symfony/polyfill-intl-idn component backports PHP features for internationalized domain names. Versions from 1.17.1 to 1.38.1 improperly accept xn-- labels whose Punycode payload is empty or decodes to ASCII-only characters, violating the UTS #46 revision 33 standard that requires at least one non-ASCII code point in decoded ACE labels. This can cause domain names that should be distinct to be considered equal, enabling issues such as blacklist bypass, inconsistent URL parsing, and server-side request forgery in applications using the polyfill for hostname processing. The vulnerability is resolved in version 1.38.1.
Potential Impact
Applications using affected versions of symfony/polyfill-intl-idn to canonicalize or compare hostnames may incorrectly treat distinct domain names as equal. This can lead to security issues including bypassing domain-based blacklists, inconsistent URL parsing, and server-side request forgery. There are no known exploits in the wild at this time.
Mitigation Recommendations
Upgrade symfony/polyfill-intl-idn to version 1.38.1 or later, where this issue is fixed. Patch status is confirmed by the vendor advisory indicating the fix in 1.38.1. No other mitigations are specified.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-46644
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:18.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Database Specific Severity
- null
- Cvss Version
- 4.0
Threat ID: 6a58b49a68715ace43da82f6
Added to database: 07/16/2026, 10:38:18 UTC
Last enriched: 07/16/2026, 12:29:26 UTC
Last updated: 07/16/2026, 12:29:26 UTC
Views: 2
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