CVE-2026-6757Network attack vector

Unspecified impact via invalid WebAssembly pointer

Published Apr 21, 2026 · Updated Apr 21, 2026

Invalid-pointer access in Mozilla Firefox and Thunderbird before 150 allows remote attackers to cause unspecified impact. Mozilla identifies the JavaScript WebAssembly component but has not disclosed the pointer's concrete locus, how it becomes invalid, or the operation performed through it. CISA assesses that exploitation requires user interaction; ESR releases before 140.10 are also affected, and no more specific consequence is published.

CVSS severity6.3
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Invalid-pointer access in Mozilla Firefox and Thunderbird before 150 allows remote attackers to cause unspecified impact. Mozilla identifies the JavaScript WebAssembly component but has not disclosed the pointer's concrete locus, how it becomes invalid, or the operation performed through it. CISA assesses that exploitation requires user interaction; ESR releases before 140.10 are also affected, and no more specific consequence is published.

The record

CVE
CVE-2026-6757
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-824, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-824Access of Uninitialized Pointer
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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