Is CVE-2025-6435 in the CISA KEV catalog?

No. CVE-2025-6435 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-6435?

CVE-2025-6435 has a CVSS v3 base score of 8.1 (HIGH).

What is the EPSS score for CVE-2025-6435?

CVE-2025-6435 has an EPSS score of 0.38% (29th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2025-6435

HIGH

8.1

CVSS v3

NVD

Description

If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

CWE-434Unrestricted File Upload

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.38%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

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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.