CVE-2025-9187 | Memory safety bugs fixed in Firefox 142 and Thunderbird 142

Memory safety bugs present in Firefox 141 and Thunderbird 141. 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 142 and Thunderbird 142.

Published: 2025-08-19 Last update: 2026-04-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-9187 is rated Moderate Risk (45.3/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.06%). 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-2025-9187

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 2025-08-25 0.02% 0.06% +0.04%
2 2025-08-20 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-9187

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 [email protected]
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-2025-9187

OS Trackers for CVE-2025-9187

vendor priority summary link
alpine — CVE-2025-9187: 2 source package rows (firefox, thunderbird); 228 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 228. https://security.alpinelinux.org/vuln/CVE-2025-9187
debian not yet assigned CVE-2025-9187 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-2025-9187
redhat high — https://access.redhat.com/security/cve/CVE-2025-9187
suse high CVE-2025-9187 severity important: SUSE including 89 source package names (2.0.4-3.5.412:libfreebl3-3.112.2-150400.3.60.1, 2.0.4-3.5.412:libsoftokn3-3.112.2-150400.3.60.1, …), 1038 product×package rows across 224 product lines (Container bci/kiwi, Container suse/manager/5.0/x86_64/server, … (224 product lines)): Fixed 1038. https://www.suse.com/security/cve/CVE-2025-9187/
ubuntu medium CVE-2025-9187 medium priority: Ubuntu including 9 source packages (firefox, mozjs102, …), 49 status rows across 7 suites (bionic, focal, jammy, noble, plucky, questing, upstream): DNE 22, needs-triage 10, ignored 9, not-affected 8. https://ubuntu.com/security/CVE-2025-9187

Affected software / configurations for CVE-2025-9187

Vendor Product Version Raw CPE
mozilla firefox < 142.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
mozilla thunderbird < 142.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

References for CVE-2025-9187

cvelogic Threat Intelligence