Home/CVE/Denial-of-service in the Libraries component in NSS. This vulnerability was fixed in Firefox 149 and Thunderbird 149.
CVE

CVE-2026-4727

Denial-of-service in the Libraries component in NSS. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

Denial-of-service in the Libraries component in NSS. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

HIGH · CVSS 7.5 EPSS 0.0002
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules1 YARA rules0
⬡

Weakness Classification

CWE-400Uncontrolled Resource Consumption
▤

Affected Products & Versions

2
mozilla firefox< 149.0
mozilla thunderbird< 149.0
◈

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

7.5
HIGH · 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 NVD24 Mar 2026 · 01:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
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

2
suse-csafopenSUSE-SU-2026:10458-1
mozilla-mfsaMFSA2026-20
🔗

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/show_bug.cgi?id=2008112Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-20/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-23/Vendor Advisory
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