Use-after-free while manipulating DOM events and removing audio elements due to errors in the handling of node adoption. This vulnerability affects Firefox < 50.1, Firefox ESR < 45.6, and Thunderbird < 45.6.
CVE-2016-9899
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8(medium)
- EG Risk
- 65(Track*)EG Risk 65/100SSVC: Track*
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity98% × 45%Exploitation40% × 40%Automatability30% × 15%Action: Watch closely — could escalate to Attend. - EPSS PROB
- 21%
- EPSS %ILE
- 97%
- KEV
- Not listed
Published
June 11, 2018
Last Modified
November 25, 2025
Advisory Details (10)
Auto-updated Aug 20, 2026Security vulnerabilities fixed in Firefox ESR 45.6 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2016-95/Security vulnerabilities fixed in Firefox 50.1 — Mozilla
https://www.mozilla.org/security/advisories/mfsa2016-94/Mozilla Firefox < 50.1.0 - Use-After-Free - Windows dos Exploit
https://www.exploit-db.com/exploits/41042/Mozilla Firefox, Thunderbird: Multiple vulnerabilities (GLSA 201701-15) — Gentoo security
https://security.gentoo.org/glsa/201701-151317409 - (CVE-2016-9899) UAF involving mutation events, contenteditable iframes and adding and immediately removing audio elements
https://bugzilla.mozilla.org/show_bug.cgi?id=1317409Patch Availability(4)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| ubuntu | firefox (50.1.0+build2-0ubuntu0.16.10.1) @ yakkety | 2026-05-28 | ubuntu |
| ubuntu | thunderbird (1:45.7.0+build1-0ubuntu0.16.10.1) @ yakkety | 2026-05-28 | ubuntu |
| redhat | thunderbird-0:45.6.0-1.el7_3 | 2016-12-21 | redhat |
| redhat | firefox-0:45.6.0-1.el7_3 | 2016-12-14 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(8 across 6 ecosystems)
Debian:7(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | 45.0.1esr-1 ... 45.5.1esr-1~deb8u1 (24 versions) | 45.6.0esr-1~deb7u1 | — |
| icedove | 10.0.12-1 ... 44.0~b1-1 (126 versions) | 1:45.6.0-2~deb7u1 | — |
Debian:8(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | 45.0.1esr-1 ... 45.6.0esr-1~deb7u1 (25 versions) | 45.6.0esr-1~deb8u1 | — |
| icedove | 1:45.0~b4-1 ... 44.0~b1-1 (70 versions) | 1:45.6.0-1~deb8u1 | — |
Debian:11(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | — | 45.6.0esr-1 | — |
Debian:12(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | — | 45.6.0esr-1 | — |
Debian:13(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | — | 45.6.0esr-1 | — |
Debian:14(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| firefox-esr | — | 45.6.0esr-1 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(4)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
Data Freshness Timeline
(refreshed 4× in last 7d / 22× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 106 total refreshes for this CVE.
- 2026-08-25 13:44 UTCEPSS rescore
- 2026-08-22 15:07 UTCOSV refresh
- 2026-08-21 23:44 UTCEPSS rescore
- 2026-08-19 16:59 UTCEPSS rescore
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- 2026-08-06 19:05 UTCOSV refresh
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- 2026-07-23 14:15 UTCEPSS rescore
- 2026-07-23 01:24 UTCEG score recompute
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- 2026-07-21 11:17 UTCOSV refresh
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- 2026-07-04 06:56 UTCOSV refresh
- 2026-07-04 06:28 UTCEPSS rescore
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- 2026-06-15 18:13 UTCOSV refresh
- 2026-06-15 17:45 UTCEPSS rescore
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- 2026-06-13 22:57 UTCEPSS rescore
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- 2026-06-12 23:09 UTCEPSS rescore
- 2026-06-11 13:57 UTCEPSS rescore
- 2026-06-08 14:14 UTCEPSS rescore
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- 2026-06-07 15:22 UTCEPSS rescore
- 2026-06-06 13:45 UTCEPSS rescore
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- 2026-05-28 13:42 UTCEPSS rescore
- 2026-05-28 06:59 UTCEG score recompute
Publicly available exploits
(1 reference)Working exploit code is in the public domain (1 Exploit-DB entry). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.
- Exploit-DBEDB-41042First seen Jan 13, 2017
Mozilla Firefox < 50.1.0 - Use-After-Free
Open source ↗
Frequently asked(5)
What is CVE-2016-9899?
When was CVE-2016-9899 disclosed?
Is CVE-2016-9899 actively exploited?
What is the CVSS score of CVE-2016-9899?
How do I remediate CVE-2016-9899?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2016-9899
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