CVE-2025-0247 | Memory safety bugs fixed in Firefox 134 and Thunderbird 134

Memory safety bugs present in Firefox 133 and Thunderbird 133. 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 134 and Thunderbird 134.

Published: 2025-01-07 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-0247 is rated High Risk (76.7/100): CVSS Critical severity, with high exploitation likelihood (EPSS 19.17%, 95th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +4.11% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize 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-2025-0247

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 2026-05-29 15.06% 19.17% +4.11%
2 2026-05-06 15.40% 15.06% -0.34%
3 2026-04-21 — 15.40% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-0247

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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: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: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.
 3.9 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-0247

OS Trackers for CVE-2025-0247

vendor priority summary link
alpine — CVE-2025-0247: 2 source package rows (firefox, thunderbird); 195 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 195. https://security.alpinelinux.org/vuln/CVE-2025-0247
debian not yet assigned CVE-2025-0247 not yet assigned priority: Debian including 1 source packages (firefox), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2025-0247
gentoo high CVE-2025-0247: 1 GLSA(s) (202501-10), 2 atom(s) (www-client/firefox, www-client/firefox-bin); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2025-0247
redhat high — https://access.redhat.com/security/cve/CVE-2025-0247
suse high — https://www.suse.com/security/cve/CVE-2025-0247/
ubuntu medium CVE-2025-0247 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 10, not-affected 9, released 2. https://ubuntu.com/security/CVE-2025-0247

Affected software / configurations for CVE-2025-0247

Vendor Product Version Raw CPE
mozilla firefox < 134.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
mozilla thunderbird < 134.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

References for CVE-2025-0247

cvelogic Threat Intelligence