CVE-2025-1935 [Medium] | XSS in Firefox

CVE-2025-1935 is rated Low Risk (31.3/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.19%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-12	0.30%	0.19%	-0.11%
2	2026-01-15	0.36%	0.30%	-0.06%
3	2025-12-29	—	0.36%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-12

0.30%

0.19%

-0.11%

2026-01-15

0.36%

0.30%

-0.06%

2025-12-29

—

0.36%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/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:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. 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:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.	2.8	1.4	134c704f-9b21-4f2e-91b3-4a467353bcc0

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/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:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N): Data isn’t meaningfully altered or forged.
Availability (A:N): Service keeps running; no real outage angle.

2.8

1.4

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

OS Trackers for CVE-2025-1935

vendor	priority	summary	link
`alpine`	—	CVE-2025-1935: 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-2025-1935
`debian`	not yet assigned	CVE-2025-1935 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-2025-1935
`gentoo`	high	CVE-2025-1935: 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-2025-1935
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2025-1935
`suse`	high	CVE-2025-1935 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-2025-1935/
`ubuntu`	medium	CVE-2025-1935 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-2025-1935

Affected software / configurations for CVE-2025-1935

Vendor	Product	Version	Raw CPE
mozilla	firefox	< 128.8.0	cpe:2.3:a:mozilla:firefox:::::esr:::*
mozilla	firefox	< 136.0	cpe:2.3:a:mozilla:firefox::::::::
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-2025-1935

URL	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1866661	Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2025-14/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-16/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-17/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-18/	Vendor Advisory
https://lists.debian.org/debian-lts-announce/2025/03/msg00006.html

URL

CVE-2025-1935 | Clickjacking the registerProtocolHandler info-bar

Exploit prediction scoring system (EPSS) score for CVE-2025-1935

Common vulnerability scoring system (CVSS) metrics for CVE-2025-1935

Weakness enumeration for CVE-2025-1935

OS Trackers for CVE-2025-1935

Affected software / configurations for CVE-2025-1935

References for CVE-2025-1935