Process-memory disclosure via unchecked DKIM body-hash length
Published May 6, 2021 · Updated Aug 4, 2024
Out-of-bounds read in Exim 4 before 4.94.2 allows remote attackers to expose process memory through a crafted DKIM-Signature header. In pdkim_finish_bodyhash, memcmp uses the computed hash length without confirming that the attacker-controlled signature hash is equally long. Disclosure requires the nondefault acl_smtp_dkim setting; otherwise, the demonstrated consequence is a heap over-read during DKIM verification.
Summary
What happened
Out-of-bounds read in Exim 4 before 4.94.2 allows remote attackers to expose process memory through a crafted DKIM-Signature header. In pdkim_finish_bodyhash, memcmp uses the computed hash length without confirming that the attacker-controlled signature hash is equally long. Disclosure requires the nondefault acl_smtp_dkim setting; otherwise, the demonstrated consequence is a heap over-read during DKIM verification.
The record
- CVE
- CVE-2020-28025
- Published
- May 6, 2021
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-125, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 6, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Published CVSS scores
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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.
Public exploit references
- 21Nails CVE-2020-28025 proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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