Email-content disclosure via inherited CSS rules
Published Jan 28, 2026 · Updated Jan 28, 2026
Information disclosure in Mozilla Thunderbird before 147.0.1 or ESR before 140.7.1 allows remote attackers to extract decrypted email content. Thunderbird renders explicitly decrypted inline OpenPGP text in the outer HTML message's styling context, letting sender-controlled CSS rules, fonts, and animations probe secret text through remote-resource requests. Exploitation requires a crafted email, explicit decryption by the recipient, and permission to load its remote content; the demonstrated consequence is disclosure of the decrypted text.
Summary
What happened
Information disclosure in Mozilla Thunderbird before 147.0.1 or ESR before 140.7.1 allows remote attackers to extract decrypted email content. Thunderbird renders explicitly decrypted inline OpenPGP text in the outer HTML message's styling context, letting sender-controlled CSS rules, fonts, and animations probe secret text through remote-resource requests. Exploitation requires a crafted email, explicit decryption by the recipient, and permission to load its remote content; the demonstrated consequence is disclosure of the decrypted text.
The record
- CVE
- CVE-2026-0818
- Published
- Jan 28, 2026
- Updated
- Jan 28, 2026
- Vendor
- Mozilla
- Product
- Thunderbird
- Classifications
- CWE-200, CWE-352, CWE-116, T1566
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 28, 2026CVE publishedPublication date reported by the CVE source.
- Jan 28, 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 <140.7.1
- Affected versionversion=unspecified <147.0.1
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
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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