Email disclosure via S/MIME fail-open state handling
Published Sep 11, 2023 · Updated Jun 25, 2025
Information disclosure in Mail in Apple macOS Monterey before 12.6.8 allows attackers to obtain plaintext from S/MIME email. Mail's compose pipeline carries the requested encryption state incorrectly when message format, reply, or quoting state changes, then emits plaintext without warning. Exposure requires a user to send an S/MIME message through an affected composition path, revealing its contents to recipients or network observers.
Summary
What happened
Information disclosure in Mail in Apple macOS Monterey before 12.6.8 allows attackers to obtain plaintext from S/MIME email. Mail's compose pipeline carries the requested encryption state incorrectly when message format, reply, or quoting state changes, then emits plaintext without warning. Exposure requires a user to send an S/MIME message through an affected composition path, revealing its contents to recipients or network observers.
The record
- CVE
- CVE-2023-40440
- Published
- Sep 11, 2023
- Updated
- Jun 25, 2025
- Vendor
- Apple
- Product
- macOS
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 11, 2023CVE publishedPublication date reported by the CVE source.
- Jun 25, 2025Record 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 <12.6
What conditions does exploitation require?
What is affected?
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
No sourced classifications are available.
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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