Memory corruption via text rendering integer overflow
Published Apr 7, 2026 · Updated Apr 7, 2026
Integer overflow in Firefox before 149.0.2, Firefox ESR before 140.9.1, and Thunderbird before 149.0.2 allows remote attackers to corrupt memory. Thunderbird's 140 ESR branch is also affected before 140.9.1; Mozilla has disclosed incorrect boundary conditions in Graphics: Text but not the affected function or arithmetic operation. Exploitation requires interaction with attacker-controlled content, while Thunderbird mail-reading mode disables scripting and limits exposure to browser-like contexts.
Summary
What happened
Integer overflow in Firefox before 149.0.2, Firefox ESR before 140.9.1, and Thunderbird before 149.0.2 allows remote attackers to corrupt memory. Thunderbird's 140 ESR branch is also affected before 140.9.1; Mozilla has disclosed incorrect boundary conditions in Graphics: Text but not the affected function or arithmetic operation. Exploitation requires interaction with attacker-controlled content, while Thunderbird mail-reading mode disables scripting and limits exposure to browser-like contexts.
The record
- CVE
- CVE-2026-5732
- Published
- Apr 7, 2026
- Updated
- Apr 7, 2026
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-190, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 7, 2026CVE publishedPublication date reported by the CVE source.
- Apr 7, 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.
- Affected versionversion=unspecified <149.0.2
What conditions does exploitation require?
What is affected?
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
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Technologies
Your stack
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Your stack
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