Server impersonation via skipped hostname verification
Published Mar 25, 2025 · Updated Mar 25, 2025
Improper certificate validation in Mbed TLS before 2.28.10 and 3.0.0 through 3.6.2 allows man-in-the-middle attackers to impersonate servers. The TLS client silently skips matching the end certificate to an expected name when mbedtls_ssl_set_hostname() was not called. Exploitation requires an active network position, certificate-based authentication, and a certificate from a trusted CA; it permits reading and modifying data exchanged over TLS.
Summary
What happened
Improper certificate validation in Mbed TLS before 2.28.10 and 3.0.0 through 3.6.2 allows man-in-the-middle attackers to impersonate servers. The TLS client silently skips matching the end certificate to an expected name when mbedtls_ssl_set_hostname() was not called. Exploitation requires an active network position, certificate-based authentication, and a certificate from a trusted CA; it permits reading and modifying data exchanged over TLS.
The record
- CVE
- CVE-2025-27809
- Published
- Mar 25, 2025
- Updated
- Mar 25, 2025
- Vendor
- TrustedFirmware.org
- Product
- Mbed TLS
- Classifications
- CWE-1188, T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 25, 2025CVE publishedPublication date reported by the CVE source.
- Mar 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=0 <2.28.10
- Affected versionversion=3.0.0 <3.6.3
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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