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.
CVE-2026-46644
MEDIUMPre-NVD 6.96.9—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 6.9 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.9Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.9
- EG Score
- 6.9(medium)
- EPSS
- 31.7%
- KEV
- Not listed
Published
May 28, 2026
Last Modified
July 15, 2026
Advisory Details (3)
Auto-updated Jul 15, 2026🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available
symfony/polyfill-intl-idn accepts xn-- labels whose Punycode payload decodes to ASCII-only: insecure equivalence · Advisory · symfony/polyfill · GitHub
https://github.com/symfony/polyfill/security/advisories/GHSA-2xf4-cg6j-vhgqgithub_release Patch Available
v1.38.1
Patch available: symfony/polyfill v1.38.1
https://github.com/symfony/polyfill/releases/tag/v1.38.1github_commit Patch Available
commit 1be936e2491c (symfony/polyfill)
Patch available: symfony/polyfill v1.38.1 (contains commit 1be936e2491c)
https://github.com/symfony/polyfill/commit/1be936e2491ccebe152bd736dfc91eb1422c8becVendor Advisories for CVE-2026-46644(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(2 across 1 ecosystem)
Packagist(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| symfony/polyfill | v1.17.1 ... v1.38.0 (24 versions) | 1.38.1 | — |
| symfony/polyfill-intl-idn | v1.17.1 ... v1.37.0 (22 versions) | 1.38.1 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-16 02:41 UTCEG score recompute
- 2026-07-15 16:57 UTCEPSS rescore
- 2026-07-14 21:16 UTCEG score recompute▲ 6.90
- 2026-07-14 21:15 UTCMITRE cvelistV5CVSS v3 → 6.9 · CVSS v4 → 6.9 · severity → MEDIUM
- 2026-06-15 07:55 UTCEG score recompute
- 2026-06-14 23:18 UTCEPSS rescore
- 2026-06-13 23:00 UTCEPSS rescore
- 2026-06-12 23:12 UTCEPSS rescore
- 2026-05-28 20:06 UTCEG score recompute
Frequently asked(5)
What is CVE-2026-46644?
CVE-2026-46644 is a medium vulnerability published on May 28, 2026. 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…
When was CVE-2026-46644 disclosed?
CVE-2026-46644 was first published in the National Vulnerability Database on May 28, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-46644 actively exploited?
CVE-2026-46644 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 31.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-46644?
CVE-2026-46644 has a CVSS v3 base score of 6.9 (NVD).
How do I remediate CVE-2026-46644?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-46644, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-46644
Is Your Infrastructure Affected by CVE-2026-46644?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.