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Critical· 9.8official fix available

CVE-2026-16408

An integer overflow in Mozilla Firefox's Audio/Video Playback component (CVE-2026-16408) could allow an attacker to compromise confidentiality, integrity, and availability. The issue was resolved in Firefox 153 (and Thunderbird 153). Users should upgrade to those versions or later.

publishedJul 21, 2026
last modifiedJul 22, 2026
sourcesNVD
severity · cvss
9.8
critical · how bad it is
exploitation · epss
<1%
26th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Aug 20, 2026

An official fix is available, so this entry is kept for 30 days and then removed automatically.

01

Who is affected

Mozilla Firefox users

02

Real-world impact

Potential remote code execution or denial of service leading to loss of data or service disruption.

03

Why this severity

CVSS 3.1 base score 9.8 (Critical) due to network‑adjacent attack vector, low complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability.

04

What to do about it

official fix available
recommended steps
  1. 011. Upgrade Mozilla Firefox to version 153 or later.
  2. 022. If you use Mozilla Thunderbird, upgrade it to version 153 or later as well.

NVD-referenced vendor advisory

05

Timeline

  1. Jul 21, 2026 · 12d ago
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 21, 2026 · 11d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →