CVE-2026-2801Public exploit

Application crash via undersized WebAssembly bounds check

Published Feb 24, 2026 · Updated Feb 24, 2026

Out-of-bounds access in Mozilla Firefox and Thunderbird before 148 allows context-dependent attackers to crash the application. The IntrI8PrepareB function checks rows times columns against WebAssembly memory but omits the four-byte float element size, permitting the matrix operation to exceed the buffer. Reachability requires an installed malicious add-on able to invoke WebAssembly.mozIntGemm; guard pages make a crash the established consequence, while code execution is unproven.

CVSS severity7.5
High
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

Out-of-bounds access in Mozilla Firefox and Thunderbird before 148 allows context-dependent attackers to crash the application. The IntrI8PrepareB function checks rows times columns against WebAssembly memory but omits the four-byte float element size, permitting the matrix operation to exceed the buffer. Reachability requires an installed malicious add-on able to invoke WebAssembly.mozIntGemm; guard pages make a crash the established consequence, while code execution is unproven.

The record

CVE
CVE-2026-2801
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Mozilla
Product
Firefox
Classifications
CWE-754, T1499.004
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <148

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Mozilla · Firefoxversion=unspecified <148
Mozilla · Thunderbirdversion=unspecified <148

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

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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