secp256k1-native: Compiler-reconstructed secret-dependent branch in native scalar multiplication
CVSS score
5.9
EPSS probability
—
Risk score
0.6
Published
2 h ago
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Vulnerability description
DayBreach AI Explanation
Verified against sourcesSources read
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Evidence confidence
%55
Short explanation
secp256k1-native Ruby library contains a vulnerability where certain compiler optimizations reconstruct branchless selection into secret-dependent branches, leaking timing information about secret scalars.
The vulnerability allows attackers to statistically recover secret keys or nonces through repeated timing measurements. Because the defect resides in the compiled binary, standard source reviews can easily miss it.
What should be done?
- Follow the vendor advisory guidance.
- Update affected versions to releases containing verified fixes.
Chain of evidence and sources
secp256k1-native kütüphanesinde Point#mul veya scalar_multiply_ct üzerinden yapılan yerel sabit zamanlı skaler çarpım işlemleri gizli skaler hakkında zamanlama bilgisi sızdırabilir.
Etkilenen GCC derleyici sürümleri -O2 optimizasyon seviyesinde dallanmasız seçimi gizli bağımlı dallara dönüştürmektedir.
Show the technical text from the sources
secp256k1-native is a native C secp256k1 implementation for Ruby. In affected native builds, native constant-time scalar multiplication through `Point#mul` or `scalar_multiply_ct` can leak timing information about a secret scalar when compiled by a toolchain that reconstructs branchless selection into a branch. The `Montgomery ladder` uses `uint256_select` with an all-zeros or all-ones mask, but affected GCC builds at `-O2` recover the original condition and emit secret-dependent `je` or `jne` jumps whose timing correlates with scalar bits. This defeats the assumption behind the 0.17.0 `jp_add_internal` infinity-branch fix. A consumer must multiply a secret private key or nonce in a context where an attacker can observe timing; repeated measurements can statistically recover scalar bits. The defect is in the compiled binary, so source review or `ctgrind` on a non-reconstructing toolchain may miss it. GCC 14.3.0, 15.1.0, and 15.2.0 reproduced the branch reconstruction, and `extconf.rb` appends `-O2`. Tested GCC versions through 12.4.0 used bitwise operations and GCC 13.3.0 used constant-time `cmov`; the pure-Ruby path is not affected by this flaw and separately makes no constant-time claim. GCC 16 and clang were untested, and point releases, targets, and flag combinations were not exhaustively bisected. `Earlier pre-0.17.0 versions had different constant-time issues rather than this introduced select idiom.` Version 0.18.0 contains the verified fix. The advisory's broad pre-0.18.0 guidance also covers earlier, different constant-time issues; whether this CVE groups those issues or only the select idiom introduced in 0.17.0 remains unresolved.
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CWE: CWE-208, CWE-1255
This explanation was compiled automatically from the source records. Scores, active exploitation, patch and exploit status come straight from the sources.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-63410 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | sgbett | secp256k1-native | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 5.9 | CVSS V3_1 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N | CVE CNA |
| 5.9 | CVSS V31 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-63410 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-63410 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
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