CVE-2026-4723

CRITICALNVD 9.89.8—

9.8

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

CVSS v3: 9.8
EG Score: 9.8(medium)
EPSS: 6.8%
KEV: Not listed

Published

March 24, 2026

Last Modified

April 13, 2026

Advisory Details (3)

Auto-updated May 20, 2026

No patch confirmed yet.

generic

Security Vulnerabilities fixed in Thunderbird 149 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-23/

generic

Security Vulnerabilities fixed in Firefox 149 — Mozilla

https://www.mozilla.org/security/advisories/mfsa2026-20/

generic

Access Denied

https://bugzilla.mozilla.org/show_bug.cgi?id=2013573

Data Freshness Timeline

(refreshed 12× in last 7d / 17× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-31 22:30 UTCepss_batch
2026-05-31 22:30 UTCepss_batch
2026-05-31 00:16 UTCepss_batch
2026-05-31 00:16 UTCepss_batch
2026-05-29 13:44 UTCepss_batch
2026-05-29 13:44 UTCepss_batch
2026-05-28 13:44 UTCepss_batch
2026-05-28 13:44 UTCepss_batch
2026-05-27 13:40 UTCepss_batch
2026-05-27 13:40 UTCepss_batch
2026-05-26 13:44 UTCepss_batch
2026-05-26 07:18 UTCepss_batch
2026-05-21 22:43 UTCepss_batch
2026-05-20 22:38 UTCepss_batch
2026-05-20 20:32 UTCEG score recompute
2026-05-20 20:32 UTCGHSA enrichment
2026-05-20 11:22 UTCepss_batch

Frequently asked(5)

What is CVE-2026-4723?

CVE-2026-4723 is a critical vulnerability published on March 24, 2026. Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

When was CVE-2026-4723 disclosed?

CVE-2026-4723 was first published in the National Vulnerability Database on March 24, 2026, with the most recent update on April 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2026-4723 actively exploited?

CVE-2026-4723 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 6.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2026-4723?

CVE-2026-4723 has a CVSS v3 base score of 9.8 (NVD).

How do I remediate CVE-2026-4723?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4723, 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

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CVE-2026-4723

📅 Published

🔄 Last Modified

📋 Advisory Details (3)

Security Vulnerabilities fixed in Thunderbird 149 — Mozilla

Security Vulnerabilities fixed in Firefox 149 — Mozilla

Access Denied

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2026-4723?

Published

Last Modified

Advisory Details (3)

Frequently asked(5)