Is CVE-2025-1935 in the CISA KEV catalog?

No. CVE-2025-1935 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-1935?

CVE-2025-1935 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2025-1935?

CVE-2025-1935 has an EPSS score of 0.32% (23th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-1935?

Upgrade firefox on debian unstable to 136.0-1 or later. Fixes are available for 14 affected products.

CVE & CISA-KEV Catalog

CVE-2025-1935

MEDIUM

4.3

CVSS v3

NVD

Description

A web page could trick a user into setting that site as the default handler for a custom URL protocol. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

firefoxDebian

Fixed in:136.0-1CVE-2025-1935

firefoxRed Hat / RHEL

Fixed in:0:128.8.0-1.el7_9RHSA-2025:2699

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

firefoxRocky

Fixed in:0:128.8.0-1.el7_9RHSA-2025:2699

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

firefox-debuginfoRed Hat / RHEL

Fixed in:0:128.8.0-1.el7_9RHSA-2025:2699

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

firefox-debuginfoRocky

Fixed in:0:128.8.0-1.el7_9RHSA-2025:2699

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

firefox-debugsourceRocky

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

firefox-debugsourceRed Hat / RHEL

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_10RHSA-2025:2452

Fixed in:0:128.8.0-1.el8_8RHSA-2025:2486

Fixed in:0:128.8.0-1.el8_2RHSA-2025:2708

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el8_4RHSA-2025:2484

Fixed in:0:128.8.0-1.el8_6RHSA-2025:2485

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_0RHSA-2025:2481

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

firefox-x11Red Hat / RHEL

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

firefox-x11Rocky

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_2RHSA-2025:2480

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

Fixed in:0:128.8.0-1.el9_5RHSA-2025:2359

Fixed in:0:128.8.0-1.el9_4RHSA-2025:2479

firefoxUbuntu

Fixed in:136.0+build3-0ubuntu0.20.04.1USN-7334-1

thunderbirdUbuntu

Fixed in:1:128.12.0+build1-0ubuntu0.22.04.1USN-7663-1

DeveloperEditionWindows application

Affected:136.0Fixed in:136.0Mozilla

Affected:128.8.0Fixed in:128.8.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:136.0Fixed in:136.0Mozilla

Affected:128.8.0Fixed in:128.8.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:129.0 136.0Fixed in:136.0Mozilla

Affected:128.8.0Fixed in:128.8.0Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Exploit Intelligence

0.32%probability of exploitation in 30 days

23rdpercentile

Low risk: more likely to be exploited than 23% of all known CVEs.

References

Vendor Advisory4

Issue Tracking1

bugzilla.mozilla.org

Other references1

lists.debian.org

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-13.