Information disclosure via plaintext handshake message buffering
Published Jan 28, 2026 · Updated Jan 28, 2026
Improper TLS 1.3 message handling in Go crypto/tls before 1.24.12 and 1.25.0 through 1.25.5 allows attackers to infer an ECH ServerName. The initial-hello path buffers concatenated messages without requiring an empty buffer before the encryption-level transition, so a later plaintext message is consumed after encrypted processing begins. A network-local on-path attacker must modify handshake traffic; transcript mismatch then fails the handshake, but the response can reveal the inner ClientHello ServerName.
Summary
What happened
Improper TLS 1.3 message handling in Go crypto/tls before 1.24.12 and 1.25.0 through 1.25.5 allows attackers to infer an ECH ServerName. The initial-hello path buffers concatenated messages without requiring an empty buffer before the encryption-level transition, so a later plaintext message is consumed after encrypted processing begins. A network-local on-path attacker must modify handshake traffic; transcript mismatch then fails the handshake, but the response can reveal the inner ClientHello ServerName.
The record
- CVE
- CVE-2025-61730
- Published
- Jan 28, 2026
- Updated
- Jan 28, 2026
- Vendor
- Go
- Product
- crypto/tls
- Classifications
- CWE-940, T1557
- 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=0 <1.24.12
- Affected versionversion=1.25.0 <1.25.6
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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