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CVE-2026-2780

32
FAUCET Score

CVE-2026-2780 is a critical privilege escalation vulnerability in the Netmonitor component affecting Mozilla Firefox versions prior to 148, Firefox ESR prior to 140.8, and Thunderbird versions prior to 148 and 140.8. With a CVSS score of 9.8, this vulnerability is remotely exploitable without user interaction, allowing for complete compromise of confidentiality, integrity, and availability. While no public exploit code or active exploitation has been observed, the vulnerability has garnered some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 140.8.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
< 148.0CPE matchmatch criteria
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
< 140.8.0CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
< 148.0CPE matchmatch criteria
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.34%
Probability of exploitation in next 30 days
EPSS Percentile
26.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0034 is in the 5th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (12)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: firefox-0:140.8.0-2.el9_7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: firefox-0:140.8.0-2.el10_1
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox-0:140.8.0-2.el8_10
View patch
mozillavendor investigatingvia nvd_reference
View patch
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: thunderbird
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: rhel10/thunderbird-flatpak
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: thunderbird
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: thunderbird
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: firefox
redhatno patchvia redhat_api
Product: Red Hat Enterprise Linux 10Fixed in: rhel10/firefox-flatpak

Vendor Advisories (1)

redhatCVE-2026-2780Moderate

firefox: Privilege escalation in the Netmonitor component

Feb 24, 2026

References

bugzilla.mozilla.org / show_bug.cgi
Issue TrackingPermissions Required
mozilla.org / security/advisories/mfsa2026-13
Vendor Advisory
mozilla.org / security/advisories/mfsa2026-15
Vendor Advisory
mozilla.org / security/advisories/mfsa2026-16
Vendor Advisory
mozilla.org / security/advisories/mfsa2026-17
Vendor Advisory