CVE-2025-1931 | Use-after-free in WebTransportChild

It was possible to cause a use-after-free in the content process side of a WebTransport connection, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Published: 2025-03-04 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-1931 is rated Moderate Risk (51/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.39%). 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-2025-1931

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 2026-04-19 0.32% 0.39% +0.07%
2 2026-04-12 0.49% 0.32% -0.17%
3 2026-03-02 — 0.49% —

Full EPSS history (17 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-1931

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-1931

OS Trackers for CVE-2025-1931

vendor priority summary link
alpine — CVE-2025-1931: 3 source package rows (firefox, firefox-esr, thunderbird); 342 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 342. https://security.alpinelinux.org/vuln/CVE-2025-1931
debian not yet assigned CVE-2025-1931 not yet assigned priority: Debian including 3 source packages (firefox, firefox-esr, thunderbird), 11 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 11. https://security-tracker.debian.org/tracker/CVE-2025-1931
gentoo high CVE-2025-1931: 3 GLSA(s) (202505-02, 202505-03, 202505-08), 5 atom(s) (dev-lang/spidermonkey, mail-client/thunderbird, mail-client/thunderbird-bin, www-client/firefox, www-client/firefox-bin); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2025-1931
redhat high — https://access.redhat.com/security/cve/CVE-2025-1931
suse high CVE-2025-1931 severity important: SUSE including 38 source package names (MozillaFirefox-128.8.0-112.249.3, MozillaFirefox-128.8.0-150200.152.173.1, …), 140 product×package rows across 48 product lines (Container suse/kiosk/firefox-esr, Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, … (48 product lines)): Fixed 140. https://www.suse.com/security/cve/CVE-2025-1931/
ubuntu medium CVE-2025-1931 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 65 status rows across 8 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream): DNE 34, ignored 10, needs-triage 9, not-affected 9, released 3. https://ubuntu.com/security/CVE-2025-1931

Affected software / configurations for CVE-2025-1931

Vendor Product Version Raw CPE
mozilla firefox < 115.21.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla firefox < 136.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
mozilla firefox >= 116.0, < 128.8.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla thunderbird < 128.8.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
mozilla thunderbird >= 129.0, < 136.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

References for CVE-2025-1931

cvelogic Threat Intelligence