Signature rejection via uncoerced small ECDSA integers
Published Jun 7, 2020 · Updated Aug 4, 2024
Improper signature verification in Crypt::Perl before 0.32 allows attackers to cause valid secp256r1 ECDSA signatures to be rejected. The Crypt::Perl::ECDSA::KeyBase::_verify routine uses decoded r and s values in BigInt-dependent checks without first coercing small integers to Crypt::Perl::BigInt. The condition requires a valid signature with small r and s values, including s = 1; the demonstrated consequence is verification failure, not acceptance of a forgery.
Summary
What happened
Improper signature verification in Crypt::Perl before 0.32 allows attackers to cause valid secp256r1 ECDSA signatures to be rejected. The Crypt::Perl::ECDSA::KeyBase::_verify routine uses decoded r and s values in BigInt-dependent checks without first coercing small integers to Crypt::Perl::BigInt. The condition requires a valid signature with small r and s values, including s = 1; the demonstrated consequence is verification failure, not acceptance of a forgery.
The record
- CVE
- CVE-2020-13895
- Published
- Jun 7, 2020
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- Unavailable
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jun 7, 2020CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record updatedLatest update available in the CVE record.
Exploitability
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