CVE-2025-1938 | Memory safety bugs fixed in Firefox 136, Thunderbird 136, Firefox ESR 128.8, and Thunderbird 128.8

Memory safety bugs present in Firefox 135, Thunderbird 135, Firefox ESR 128.7, and Thunderbird 128.7. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 136, 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-2025-1938 is rated Moderate Risk (45/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.32%). 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-2025-1938

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 2026-03-02 0.36% 0.32% -0.04%
2 2025-12-19 0.30% 0.36% +0.06%
3 2025-11-24 — 0.30% —

Full EPSS history (8 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-1938

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N 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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.5 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-1938

OS Trackers for CVE-2025-1938

vendor priority summary link
alpine — CVE-2025-1938: 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-2025-1938
debian not yet assigned CVE-2025-1938 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-2025-1938
gentoo high CVE-2025-1938: 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-2025-1938
redhat high — https://access.redhat.com/security/cve/CVE-2025-1938
suse high CVE-2025-1938 severity important: SUSE including 34 source package names (MozillaFirefox-128.8.0-112.249.3, MozillaFirefox-128.8.0-150200.152.173.1, …), 136 product×package rows across 48 product lines (Container suse/kiosk/firefox-esr, Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, … (48 product lines)): Fixed 136. https://www.suse.com/security/cve/CVE-2025-1938/
ubuntu medium CVE-2025-1938 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, not-affected 9, needs-triage 8, released 4. https://ubuntu.com/security/CVE-2025-1938

Affected software / configurations for CVE-2025-1938

Vendor Product Version Raw CPE
mozilla firefox < 128.7.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla firefox < 135.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
mozilla thunderbird < 128.7.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
mozilla thunderbird >= 129.0, < 135.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

References for CVE-2025-1938

cvelogic Threat Intelligence