CVE-2026-7321 | Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.

Published: 2026-04-28 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-7321 is rated Moderate Risk (44.5/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.26%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-7321

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.26% +0.22%
2 2026-04-29 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-7321

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.6 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 6.0 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-7321

GitHub Security Advisory for CVE-2026-7321

GHSA-jjvw-q2ff-g9g3 · Severity: critical — Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This...

OS Trackers for CVE-2026-7321

vendor priority summary link
debian not yet assigned CVE-2026-7321 not yet assigned priority: Debian including 2 source packages (firefox-esr, thunderbird), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2026-7321
ubuntu medium CVE-2026-7321 medium priority: Ubuntu has no source package entries, 0 status rows across 0 suites (none): no status rows. https://ubuntu.com/security/CVE-2026-7321

Affected software / configurations for CVE-2026-7321

Vendor Product Version Raw CPE
mozilla firefox < 140.10.1 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla firefox < 150.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
mozilla thunderbird < 140.10.1 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
mozilla thunderbird < 150.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

References for CVE-2026-7321

cvelogic Threat Intelligence