Vulnary
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Critical· 9.8official fix available

CVE-2026-16402

CVE-2026-16402 is a critical integer overflow in the Graphics: ImageLib component of Firefox and Thunderbird that could allow remote code execution. The flaw was addressed in Firefox 153 and Thunderbird 153. No known exploitation or public exploit has been reported.

publishedJul 21, 2026
last modifiedJul 24, 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 21, 2026

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

01

Who is affected

Users of Firefox and Thunderbird prior to version 153.

02

Real-world impact

An attacker could exploit this vulnerability to execute arbitrary code on a victim's system.

03

Why this severity

With a CVSS base score of 9.8, the vulnerability is rated critical due to its network‑reachable, low‑complexity nature and full impact on confidentiality, integrity, and availability.

04

What to do about it

official fix available
recommended steps
  1. 011. Upgrade Firefox to version 153 or later.
  2. 022. Upgrade Thunderbird to version 153 or later.

NVD-referenced vendor advisory

05

Timeline

  1. Jul 21, 2026 · 12d ago
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 22, 2026 · 10d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
  3. Jul 24, 2026 · 9d ago
    Advisory updated
    The NVD record was last revised.
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 →