CVE-2026-12306Network attack vector

Information disclosure via undisclosed memory-safety flaw

Published Jun 16, 2026 · Updated Jun 16, 2026

Memory-safety flaw in Mozilla Firefox and Thunderbird before 152 or ESR 140.12 allows remote attackers to disclose limited data. Mozilla's public advisories identify only a private Bugzilla report and do not disclose the affected component or unsafe memory operation. Thunderbird email reading does not expose the flaw because scripting is disabled; browser or browser-like contexts remain at risk.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory-safety flaw in Mozilla Firefox and Thunderbird before 152 or ESR 140.12 allows remote attackers to disclose limited data. Mozilla's public advisories identify only a private Bugzilla report and do not disclose the affected component or unsafe memory operation. Thunderbird email reading does not expose the flaw because scripting is disabled; browser or browser-like contexts remain at risk.

The record

CVE
CVE-2026-12306
Published
Jun 16, 2026
Updated
Jun 16, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-119
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 16, 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

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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

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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