No exploitation reported

CVE-2016-5277

Q: Is CVE-2016-5277 actively exploited?

Active exploitation of CVE-2016-5277 has not been confirmed. Its EPSS score was 4.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2016-5277?

CVE-2016-5277 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2016-09-22
WeaknessCWE-416

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

Use-after-free vulnerability in the nsRefreshDriver::Tick function in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4, and Thunderbird < 45.4 allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption) by leveraging improper interaction between timeline destruction and the Web Animations model implementation.

Timeline

dates in UTC

2016-09-2222:59CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2016-5277?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-5277?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Mozilla firefox

Branch	Affected	Fixed in	Source
48.0	≤ 48.0.2	no fix published	NVD
45.1	= 45.1.0	no fix published	NVD
45.1	= 45.1.1	no fix published	NVD
45.2	= 45.2.0	no fix published	NVD
45.3	= 45.3.0	no fix published	NVD

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

Fix

Advisories and patches

www.mozilla.orgVendor Advisory

Detection

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

Sources

NVDCVSS 3.09.8read 2026-10-23
NVDCVSS 2.07.5read 2026-10-23
NVDweakness (CWE)CWE-416read 2026-10-23
FIRST EPSSEPSS score4.0 %2026-10-22

Technical details

CVSS v3 Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2016-09-22
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2016-5277?

Is CVE-2016-5277 actively exploited?

Active exploitation of CVE-2016-5277 has not been confirmed. Its EPSS score was 4.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2016-5277?

CVE-2016-5277 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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