Email address misinterpretation via encoded list separators
Published Feb 28, 2025 · Updated Jul 31, 2026
Improper output encoding in affected CPython releases allows remote authenticated users to make mail servers misparse address headers. The email header parser permits a ListSeparator comma to become an RFC 2047 encoded word when folding moves it onto a Unicode-encoded continuation line. Exploitation requires control of an address list processed by the email package and a downstream mail parser that treats the encoded comma as content, exposing message data through recipient confusion.
Summary
What happened
Improper output encoding in affected CPython releases allows remote authenticated users to make mail servers misparse address headers. The email header parser permits a ListSeparator comma to become an RFC 2047 encoded word when folding moves it onto a Unicode-encoded continuation line. Exploitation requires control of an address list processed by the email package and a downstream mail parser that treats the encoded comma as content, exposing message data through recipient confusion.
The record
- CVE
- CVE-2025-1795
- Published
- Feb 28, 2025
- Updated
- Jul 31, 2026
- Vendor
- Python Software Foundation
- Product
- CPython
- Classifications
- CWE-116
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 28, 2025CVE publishedPublication date reported by the CVE source.
- Jul 31, 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=0 <3.9.23
- Affected versionversion=3.10.0 <3.10.17
- Affected versionversion=3.11.0 <3.11.9
- Affected versionversion=3.12.0 <3.12.3
- Affected versionversion=3.13.0a1 <3.13.0a5
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
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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