Is CVE-2017-5456 in the CISA KEV catalog?

No. CVE-2017-5456 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2017-5456?

CVE-2017-5456 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2017-5456?

CVE-2017-5456 has an EPSS score of 2.82% (85th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2017-5456?

Upgrade firefox on debian unstable to 52.0.1-1 or later. Fixes are available for 4 affected products.

CVE & CISA-KEV Catalog

CVE-2017-5456

CRITICALEPSS 85th pctl

9.8

CVSS v3

NVD

Description

A mechanism to bypass file system access protections in the sandbox using the file system request constructor through an IPC message. This allows for read and write access to the local file system. This vulnerability affects Firefox ESR < 52.1 and Firefox < 53.

CWE-732Incorrect Permission Assignment for Critical Resource

How to fix

Remediation Available

firefoxDebian

Fixed in:52.0.1-1CVE-2017-5456

firefoxUbuntu

Fixed in:53.0+build6-0ubuntu0.14.04.1USN-3260-1

Fixed in:53.0+build6-0ubuntu0.16.04.1USN-3260-1

DeveloperEditionWindows application

Affected:52.1.0Fixed in:52.1.0Mozilla

Affected:53.0Fixed in:53.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:52.1.0Fixed in:52.1.0Mozilla

Affected:53.0Fixed in:53.0Mozilla

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 InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

2.82%probability of exploitation in 30 days

85thpercentile

Elevated risk: more likely to be exploited than 85% of all known CVEs.

References

Patch1

bugzilla.mozilla.org

Vendor Advisory2

Third-Party Advisory3

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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.