Signature forgery and key theft via libtomcrypt
Published Apr 21, 2026 · Updated Apr 21, 2026
Vulnerable dependencies in Net::Dropbear before 0.14 allow remote attackers to compromise cryptographic operations through embedded libtomcrypt. The bundled library accepts RSA signature encodings whose trailing length is unchecked and performs ECDSA scalar multiplication with cache-observable memory access. Signature forgery is remotely reachable where consuming code verifies attacker-supplied RSA material; ECDSA key recovery requires local access or a co-resident virtual machine and repeated signature observations.
Summary
What happened
Vulnerable dependencies in Net::Dropbear before 0.14 allow remote attackers to compromise cryptographic operations through embedded libtomcrypt. The bundled library accepts RSA signature encodings whose trailing length is unchecked and performs ECDSA scalar multiplication with cache-observable memory access. Signature forgery is remotely reachable where consuming code verifies attacker-supplied RSA material; ECDSA key recovery requires local access or a co-resident virtual machine and repeated signature observations.
The record
- CVE
- CVE-2025-15638
- Published
- Apr 21, 2026
- Updated
- Apr 21, 2026
- Vendor
- Jon Gentle
- Product
- Net::Dropbear
- Classifications
- CWE-1395
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 21, 2026CVE publishedPublication date reported by the CVE source.
- Apr 21, 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 <0.14
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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