CVE-2025-9185 [High] | Memory Corruption in Firefox

Memory safety bugs present in Firefox ESR 115.26, Firefox ESR 128.13, Thunderbird ESR 128.13, Firefox ESR 140.1, Thunderbird ESR 140.1, 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, Firefox ESR 115.27, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird 128.14, and Thunderbird 140.2.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.16%	0.44%	+0.28%
2	2026-06-05	0.06%	0.16%	+0.09%
3	2025-08-25	—	0.06%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.16%

0.44%

+0.28%

2026-06-05

0.06%

0.16%

+0.09%

2025-08-25

—

0.06%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.1	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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.	2.2	5.9	[email protected]
8.1	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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.	2.2	5.9	134c704f-9b21-4f2e-91b3-4a467353bcc0

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.1

3.1

HIGH

CVSS:3.1/AV:N/AC:H/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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.

2.2

5.9

[email protected]

8.1

3.1

HIGH

CVSS:3.1/AV:N/AC:H/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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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.

2.2

5.9

134c704f-9b21-4f2e-91b3-4a467353bcc0

OS Trackers for CVE-2025-9185

vendor	priority	summary	link
`alpine`	—	CVE-2025-9185: 3 source package rows (firefox, firefox-esr, thunderbird); 382 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 382.	https://security.alpinelinux.org/vuln/CVE-2025-9185
`debian`	not yet assigned	CVE-2025-9185 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-2025-9185
`redhat`	high	—	https://access.redhat.com/security/cve/CVE-2025-9185
`suse`	high	CVE-2025-9185 severity important: SUSE including 40 source package names (2.1.3-4.11:qemu-guest-agent-8.2.7-1.1, MozillaFirefox-140.2.0-112.276.1, …), 147 product×package rows across 47 product lines (Container suse/sl-micro/6.0/kvm-os-container, Image SLES12-SP5-SAP-Azure-LI-BYOS-Production, … (47 product lines)): Fixed 144, First Fixed 3.	https://www.suse.com/security/cve/CVE-2025-9185/
`ubuntu`	medium	CVE-2025-9185 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 7, released 1.	https://ubuntu.com/security/CVE-2025-9185

Affected software / configurations for CVE-2025-9185

Vendor	Product	Version	Raw CPE
mozilla	firefox	< 115.27.0	cpe:2.3:a:mozilla:firefox:::::esr:::*
mozilla	firefox	< 142.0	cpe:2.3:a:mozilla:firefox:::::-:::*
mozilla	firefox	>= 128.0, < 128.14.0	cpe:2.3:a:mozilla:firefox:::::esr:::*
mozilla	firefox	>= 140.0, < 140.2.0	cpe:2.3:a:mozilla:firefox:::::esr:::*
mozilla	thunderbird	< 128.14.0	cpe:2.3:a:mozilla:thunderbird:::::esr:::*
mozilla	thunderbird	< 142.0	cpe:2.3:a:mozilla:thunderbird:::::-:::*
mozilla	thunderbird	>= 140.0, < 140.2.0	cpe:2.3:a:mozilla:thunderbird:::::esr:::*

References for CVE-2025-9185

URL	Tags
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1970154%2C1976782%2C1977166	Broken Link
https://www.mozilla.org/security/advisories/mfsa2025-64/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-65/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-66/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-67/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-70/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-71/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-72/	Vendor Advisory
https://lists.debian.org/debian-lts-announce/2025/08/msg00016.html
https://lists.debian.org/debian-lts-announce/2025/08/msg00018.html

URL

CVE-2025-9185 | Memory safety bugs fixed in Firefox ESR 115.27, Firefox ESR 128.14, Thunderbird ESR 128.14, Firefox ESR 140.2, Thunderbird ESR 140.2, Firefox 142 and Thunderbird 142

Exploit prediction scoring system (EPSS) score for CVE-2025-9185

Common vulnerability scoring system (CVSS) metrics for CVE-2025-9185

Weakness enumeration for CVE-2025-9185

OS Trackers for CVE-2025-9185

Affected software / configurations for CVE-2025-9185

References for CVE-2025-9185