Is CVE-2016-5257 in the CISA KEV catalog?

No. CVE-2016-5257 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2016-5257?

CVE-2016-5257 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2016-5257?

CVE-2016-5257 has an EPSS score of 4.24% (90th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2016-5257?

Upgrade firefox on debian unstable to 49.0-1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2016-5257

CRITICALEPSS 90th pctl

9.8

CVSS v3

NVD

Description

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4 and Thunderbird < 45.4 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.

CWE-119Buffer Overflow

How to fix

Remediation Available

firefoxDebian

Fixed in:49.0-1CVE-2016-5257

firefoxUbuntu

Fixed in:49.0+build4-0ubuntu0.14.04.1USN-3076-1

Fixed in:49.0+build4-0ubuntu0.16.04.1USN-3076-1

thunderbirdUbuntu

Fixed in:1:45.4.0+build1-0ubuntu0.14.04.1USN-3112-1

Fixed in:1:45.4.0+build1-0ubuntu0.16.04.1USN-3112-1

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

4.24%probability of exploitation in 30 days

90thpercentile

Elevated risk: more likely to be exploited than 90% of all known CVEs.

References

Related Vulnerabilities

Other CWE-119 (Buffer Overflow) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-4966	Critical	9.4	100%	KEV + Ransom	Fix
CVE-2017-11882	High	7.8	100%	KEV + Ransom	-
CVE-2020-0796	Critical	10.0	100%	KEV + Ransom	-
CVE-2008-4250	Critical	9.8	99%	KEV	-
CVE-2017-15944	Critical	9.8	98%	KEV	Fix
CVE-2015-0014	High	10.0	97%	-	-

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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 2026-05-06.