CVE-2026-46644

MEDIUM

6.9

CVSS v4

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.

CWE-1289

How to fix

Remediation Available

php-symfony-polyfillDebian

Fixed in:1.38.1-1CVE-2026-46644

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v4 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

Impact

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploit Intelligence

0.54%probability of exploitation in 30 days

43rdpercentile

Moderate risk: more likely to be exploited than 43% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-1289 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-45179	High	7.2	2.6%	-	-
CVE-2026-48710	Medium	6.5	1.9%	-	Fix
CVE-2026-47729	Medium	6.5	1.5%	-	Fix
CVE-2025-62718	Critical	9.9	1.2%	-	Fix
CVE-2026-33515	Medium	5.3	1.0%	-	Fix
CVE-2022-0675	Medium	5.6	0.9%	-	Fix

Common questions

How do I fix CVE-2026-46644?

Upgrade php-symfony-polyfill on debian unstable to 1.38.1-1 or later.

Is CVE-2026-46644 being actively exploited?

Not that we know of. CVE-2026-46644 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.54% is the estimated probability that it will be exploited in the next 30 days. That is higher than 43% of all scored CVEs.

How severe is CVE-2026-46644?

CVE-2026-46644 has a CVSS v4 base score of 6.9, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-46644 affect?

Published advisories record a fix for php-symfony-polyfill (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-15.