Is CVE-2017-7807 in the CISA KEV catalog?

No. CVE-2017-7807 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2017-7807?

CVE-2017-7807 has a CVSS v3 base score of 8.1 (HIGH).

What is the EPSS score for CVE-2017-7807?

CVE-2017-7807 has an EPSS score of 2.14% (80th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2017-7807?

Upgrade firefox on debian unstable to 55.0-1 or later. Fixes are available for 6 affected products.

CVE & CISA-KEV Catalog

CVE-2017-7807

HIGHEPSS 80th pctl

8.1

CVSS v3

NVD

Description

A mechanism that uses AppCache to hijack a URL in a domain using fallback by serving the files from a sub-path on the domain. This has been addressed by requiring fallback files be inside the manifest directory. This vulnerability affects Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.

CWE-20Improper Input Validation

How to fix

Remediation Available

firefoxDebian

Fixed in:55.0-1CVE-2017-7807

firefoxUbuntu

Fixed in:55.0.1+build2-0ubuntu0.14.04.2USN-3391-1

Fixed in:55.0.1+build2-0ubuntu0.16.04.2USN-3391-1

thunderbirdUbuntu

Fixed in:1:52.3.0+build1-0ubuntu0.14.04.1USN-3416-1

Fixed in:1:52.3.0+build1-0ubuntu0.16.04.1USN-3416-1

DeveloperEditionWindows application

Affected:55.0Fixed in:55.0Mozilla

Affected:52.3.0Fixed in:52.3.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:52.3.0Fixed in:52.3.0Mozilla

Affected:55.0Fixed in:55.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:52.3.0Fixed in:52.3.0Mozilla

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

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Exploit Intelligence

2.14%probability of exploitation in 30 days

80thpercentile

Elevated risk: more likely to be exploited than 80% of all known CVEs.

References

Patch1

bugzilla.mozilla.org

Vendor Advisory3

Third-Party Advisory7

Related Vulnerabilities

Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-3400	Critical	10.0	100%	KEV + Ransom	-
CVE-2021-45105	Medium	5.9	100%	-	Fix
CVE-2021-44228	Critical	10.0	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2018-7600	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2020-3452	High	7.5	100%	KEV	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 2025-11-25.