Code execution via memory corruption
Published Apr 21, 2026 · Updated Apr 21, 2026
Memory-safety defects in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird ESR 140.9 allow remote attackers to execute code. The public record groups numerous defects and identifies out-of-bounds reads, out-of-bounds writes, and use-after-free conditions, but it does not disclose the individual code loci or erroneous operations. Exploitation requires user interaction and high-complexity content processing, and grants arbitrary code execution in the affected application context.
Summary
What happened
Memory-safety defects in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird ESR 140.9 allow remote attackers to execute code. The public record groups numerous defects and identifies out-of-bounds reads, out-of-bounds writes, and use-after-free conditions, but it does not disclose the individual code loci or erroneous operations. Exploitation requires user interaction and high-complexity content processing, and grants arbitrary code execution in the affected application context.
The record
- CVE
- CVE-2026-6786
- Published
- Apr 21, 2026
- Updated
- Apr 21, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-125, CWE-787, CWE-416, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 21, 2026CVE publishedPublication date reported by the CVE source.
- 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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