CVE-2026-0891Network attack vector

Arbitrary code execution via memory corruption

Published Jan 13, 2026 · Updated Jan 13, 2026

Memory safety flaws in Mozilla Firefox 146 and Firefox ESR 140.6 allow remote attackers to execute arbitrary code through memory corruption. Mozilla has not disclosed the affected code loci or the specific unsafe operations; several bugs showed evidence of memory corruption. Exploitation requires reaching a vulnerable browser code path, and successful corruption executes code in the browser context.

CVSS severity8.1
High
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory safety flaws in Mozilla Firefox 146 and Firefox ESR 140.6 allow remote attackers to execute arbitrary code through memory corruption. Mozilla has not disclosed the affected code loci or the specific unsafe operations; several bugs showed evidence of memory corruption. Exploitation requires reaching a vulnerable browser code path, and successful corruption executes code in the browser context.

The record

CVE
CVE-2026-0891
Published
Jan 13, 2026
Updated
Jan 13, 2026
Vendor
Mozilla
Product
Firefox
Classifications
CWE-119, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 13, 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 <147

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <147
Mozilla · Firefox ESRversion=unspecified <140.7

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
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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