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CVE

CVE-2021-4129

Mozilla developers and community members Julian Hector, Randell Jesup, Gabriele Svelto, Tyson Smith, Christian Holler, a

Mozilla developers and community members Julian Hector, Randell Jesup, Gabriele Svelto, Tyson Smith, Christian Holler, and Masayuki Nakano reported memory safety bugs present in Firefox 94. 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 affects Firefox < 95, Firefox ESR < 91.4.0, and Thunderbird < 91.4.0.

CRITICAL · CVSS 9.8 EPSS 0.00361
Act now
  • Public exploit or PoC is available
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules1 YARA rules0
⬡

Weakness Classification

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

Affected Products & Versions

3
mozilla firefox< 95.0
mozilla firefox esr< 91.4.0
mozilla thunderbird< 91.4.0
⚠

Public Exploits & PoCs

1
pocbugzilla.mozilla.org · buglist.cgi?bug_id=1393362%2C1736046%2C1736751%2C1737009%...bugzilla.mozilla.org
◈

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 NVD22 Dec 2022 · 08:15 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
yes
Technical impact
total
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

13
usnUSN-5248-1
usnUSN-5246-1
rhsaRHSA-2021:5055Important
rhsaRHSA-2021:5045Important
rhsaRHSA-2021:5017Important
🔗

References & Sources

3
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.mozilla.org/security/advisories/mfsa2021-52/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-53/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-54/Vendor Advisory
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