No exploitation reportedFix available

CVE-2020-35112

Q: Is CVE-2020-35112 actively exploited?

Active exploitation of CVE-2020-35112 has not been confirmed. Its EPSS score was 1.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2020-35112?

CVE-2020-35112 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-01-07
Fixed in84.0

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

If a user downloaded a file lacking an extension on Windows, and then "Open"-ed it from the downloads panel, if there was an executable file in the downloads directory with the same name but with an executable extension (such as .bat or .exe) that executable would have been launched instead. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Firefox < 84, Thunderbird < 78.6, and Firefox ESR < 78.6.

Timeline

dates in UTC

2021-01-0714:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-35112?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-35112?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mozilla firefoxversion to verify

Branch	Affected	Fixed in	Source
84.0	< 84.0	84.0	NVD

Mozilla firefox esrversion to verify

Branch	Affected	Fixed in	Source
78.6	< 78.6.0	78.6.0	NVD

Mozilla thunderbirdversion to verify

Branch	Affected	Fixed in	Source
78.6	< 78.6.0	78.6.0	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Mozilla firefox to 84.0

Advisories and patches

www.mozilla.orgVendor Advisory
www.mozilla.orgVendor Advisory
www.mozilla.orgVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.06.8read 2026-10-23
FIRST EPSSEPSS score1.3 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: 2021-01-07
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-35112?

Is CVE-2020-35112 actively exploited?

Active exploitation of CVE-2020-35112 has not been confirmed. Its EPSS score was 1.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-35112?

CVE-2020-35112 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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