Home/CVE/Memory safety bugs present in Firefox 134 and Thunderbird 134. Some of these bugs showed evidence of memory corruption a
CVE

CVE-2025-1020

Memory safety bugs present in Firefox 134 and Thunderbird 134. Some of these bugs showed evidence of memory corruption a

Memory safety bugs present in Firefox 134 and Thunderbird 134. 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 135 and Thunderbird 135.

CRITICAL · CVSS 9.8 EPSS 0.00588
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules1 YARA rules0
⬡

Weakness Classification

CWE-787Out-of-bounds Write
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

2
mozilla firefox< 135.0
mozilla thunderbird>= 131.0 and < 135.0
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
producthighSQLite Firefox Profile Data DB Access
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security@mozilla.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD04 Feb 2025 · 02:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

4
usnUSN-7991-1
usnUSN-7263-1
suse-csafopenSUSE-SU-2025:14730-1
mozilla-mfsaMFSA2025-07
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1939063%2C1942169Broken Link
https://www.mozilla.org/security/advisories/mfsa2025-07/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-11/Vendor Advisory
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