CVE-2026-2776: mozilla firefox
CVSS: 10.0v3.1CriticalModified
AliasesUBUNTU-CVE-2026-2776DEBIAN-CVE-2026-2776CGA-qx59-f5g2-jf7jCGA-w4w9-68rv-6hppCGA-98pc-4jj3-4qc9CGA-9jqx-54w8-5228
Published 24-02-2026Last modified 15-07-2026
Vulnerability summary
CVE-2026-2776 is a critical (CVSS 10.0) vulnerability in mozilla firefox. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.1% of scored vulnerabilities.
CVSS score
10.0/10
010
Critical · v3.1 (CVE.org)EPSS score
0.63%
0%100%
Low · +0.14 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 39 · Related 9DLA-4495-1DLA-4496-1DSA-6148-1DSA-6152-1MGASA-2026-0052MGASA-2026-0053OPENSUSE-SU-2026:10242-1OPENSUSE-SU-2026:10248-1OPENSUSE-SU-2026:10257-1OPENSUSE-SU-2026:20365-1OPENSUSE-SU-2026:20391-1RHSA-2026:3338RHSA-2026:3339RHSA-2026:3361RHSA-2026:3491RHSA-2026:3492RHSA-2026:3493RHSA-2026:3494RHSA-2026:3495RHSA-2026:3496RHSA-2026:3497RHSA-2026:3515RHSA-2026:3516RHSA-2026:3517RHSA-2026:3976RHSA-2026:3978RHSA-2026:3979RHSA-2026:3980RHSA-2026:3981RHSA-2026:3982RHSA-2026:3983RHSA-2026:3984RHSA-2026:4022RHSA-2026:4152RHSA-2026:4260RHSA-2026:4432SUSE-SU-2026:0812-1SUSE-SU-2026:0871-1SUSE-SU-2026:0880-1CGA-7HQG-23JR-HJCG
Timeline
- 24-02-2026PublishedVulnerability first disclosed.
- 15-07-2026Last modifiedVulnerability information updated.
Description
Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
CVSS metrics
6 scores · 6 sources · 1 versionCritical 10.0Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HSources6 sources · 7.5–10.0
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HDiffers
- OSV · DebianEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- OSV · WolfiEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- OSV · ChainguardEcosystem advisory · calculated10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- NVDNIST10.0CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS trend
Probability
0.63%
Chance of exploitation in the next 30 days
Percentile
49%
Versus all other CVEs
30-day change
+0.14 pp
From 0.48% on 20-09-2026
20-09-202620-10-2026
EPSS score0.63%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu8 products
- mozjs102All versions (No fix recorded)
- mozjs115All versions (No fix recorded)
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
- mozjs68All versions (No fix recorded)
Chainguard2 products
- firefox< 140.8.0-r0
- firefox-esr< 140.8.0-r0
Debian2 products
- firefox-esr< 140.8.0esr-1~deb12u1 | < 140.8.0esr-1~deb13u1 | < 140.8.0esr-1
- thunderbird< 1:140.8.0esr-1~deb12u1 | < 1:140.8.0esr-1~deb13u1 | < 1:140.8.0esr-1
Mozilla2 products
- firefox< 115.33.0 | < 148.0 | ≥ 128.0, < 140.8.0
- thunderbird< 140.8.0 | < 148.0
Wolfi1 product
- firefox< 140.8.0-r0
5 vendors · 15 products
