CVE-2025-0247: mozilla firefox Out-of-bounds Write
CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2025-0247CGA-g85m-vgr2-jjjhCGA-qq5x-63qr-78j2CGA-g3p8-42fh-43rxCGA-qgh7-7m6g-gvvw
Published 07-01-2025Last modified 20-05-2026
Vulnerability summary
CVE-2025-0247 is a critical (CVSS 9.8) Out-of-bounds Write vulnerability in mozilla firefox. EPSS estimates a 10.61% chance of exploitation in the next 30 days, higher than 95.7% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)EPSS score
10.61%
0%100%
Medium · +1.34 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 3 · Related 6Timeline
- 07-01-2025PublishedVulnerability first disclosed.
- 20-05-2026Last modifiedVulnerability information updated.
Description
Memory safety bugs present in Firefox 133 and Thunderbird 133. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 134 and Thunderbird 134.
CVSS metrics
5 scores · 5 sources · 1 versionCritical 9.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSourcesAll 5 agree
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · WolfiEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · ChainguardEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
10.61%
Chance of exploitation in the next 30 days
Percentile
96%
Versus all other CVEs
30-day change
+1.34 pp
From 9.27% on 18-09-2026
18-09-202618-10-2026
EPSS score10.61%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu9 products
- firefox< 134.0+build1-0ubuntu0.20.04.1
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
Chainguard2 products
- firefox< 134.0-r0
- firefox-esr< 134-r0
Mozilla2 products
- firefox< 134.0
- thunderbird< 134.0
Wolfi1 product
- firefox< 134.0-r0
4 vendors · 14 products
References
8 links- bugzilla.mozilla.org/buglist.cgi?bug_id=1835193%2C1910021%2C1919803%2C1931576%2C1931948%2C1932173REPORTBroken LinkIssue Tracking