CVE-2026-74987Network attack vector

Unspecified impact via undisclosed memory-safety defects

Published Aug 18, 2026 · Updated Aug 19, 2026

Memory-safety defects in Mozilla Firefox and Thunderbird ESR 140.13, ESR 153.0, and 153 allow remote attackers to cause unspecified impact. Mozilla reports evidence of memory corruption or another security-relevant defect across multiple internal bugs but does not disclose the affected code paths or unsafe operations. Thunderbird blocks scripting while reading email, so reachability is limited to browser or browser-like contexts; the resulting consequence is unspecified.

CVSS severity9.8
Critical
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory-safety defects in Mozilla Firefox and Thunderbird ESR 140.13, ESR 153.0, and 153 allow remote attackers to cause unspecified impact. Mozilla reports evidence of memory corruption or another security-relevant defect across multiple internal bugs but does not disclose the affected code paths or unsafe operations. Thunderbird blocks scripting while reading email, so reachability is limited to browser or browser-like contexts; the resulting consequence is unspecified.

The record

CVE
CVE-2026-74987
Published
Aug 18, 2026
Updated
Aug 19, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, CWE-119
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 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

7.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
9.8CISA ADPCVSS:3.1/AV:N/AC:L/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 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-787Out-of-bounds Write
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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