9.8

CVE-2026-4723: Use-after-free in the JavaScript Engine component

Modified
AliasesUBUNTU-CVE-2026-4723CGA-5c8m-xmr9-9mwrCGA-wx49-g45j-c8gg
Published 24-03-2026Last modified 13-04-2026

Vulnerability summary

CVE-2026-4723 is a critical (CVSS 9.8) Use After Free vulnerability in mozilla firefox. EPSS estimates a 0.62% chance of exploitation in the next 30 days, higher than 49.6% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.62%
0%100%
Low · +0.08 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:10458-1OPENSUSE-SU-2026:11373-1CGA-F853-Q3F7-W4J6

Timeline

  1. 24-03-2026
    PublishedVulnerability first disclosed.
  2. 13-04-2026
    Last modifiedVulnerability information updated.

Description

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

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.62%

Chance of exploitation in the next 30 days

Percentile

50%

Versus all other CVEs

30-day change

Increase +0.08 pp

From 0.54% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu8 products
  • mozjs102All versions (No fix recorded)
  • mozjs115All versions (No fix recorded)
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
  • mozjs68All versions (No fix recorded)
Chainguard1 product
  • firefox< 149.0-r0
Mozilla1 product
Wolfi1 product
  • firefox< 149.0-r0

4 vendors · 11 products

References

6 links