9.8

CVE-2025-1009: mozilla firefox Use After Free

CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2025-1009DEBIAN-CVE-2025-1009CGA-3m8r-6fj3-97wj
Published 04-02-2025Last modified 13-04-2026
Open JSON

Vulnerability summary

CVE-2025-1009 is a critical (CVSS 9.8) Use After Free vulnerability in mozilla firefox. EPSS estimates a 1.21% chance of exploitation in the next 30 days, higher than 67.8% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
1.21%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 34 · Related 11
DLA-4044-1DLA-4045-1DSA-5858-1DSA-5861-1MGASA-2025-0045MGASA-2025-0048

Timeline

  1. 04-02-2025
    PublishedVulnerability first disclosed.
  2. 13-04-2026
    Last modifiedVulnerability information updated.

Description

An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.

CVSS metrics

6 scores · 6 sources · 1 version

EPSS trend

Probability

1.21%

Chance of exploitation in the next 30 days

Percentile

68%

Versus all other CVEs

30-day change

0.00 pp

From 1.21% on 19-09-2026

19-09-202619-10-2026
EPSS score
1.21%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu9 products
  • firefox< 135.0+build2-0ubuntu0.20.04.1
  • mozjs102All versions (No fix recorded)
  • mozjs115All versions (No fix recorded)
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
Chainguard2 products
  • firefox< 135.0-r0
  • firefox-esr< 128.7.0-r0
Debian2 products
  • firefox-esr< 128.7.0esr-1~deb12u1 | < 128.7.0esr-1
  • thunderbird< 1:128.7.0esr-1~deb12u1 | < 1:128.7.0esr-1
Mozilla2 products
  • firefox< 115.20.0 | < 135.0 | ≥ 128.1.0, < 128.7.0
  • thunderbird≥ 128.0.1, < 128.7.0 | ≥ 131.0, < 135.0
Wolfi1 product
  • firefox< 135.0-r0

5 vendors · 16 products

References

16 links
Show all 16 references