{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63410", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-07-16T19:20:28.987Z", "datePublished": "2026-10-30T22:48:09.173Z", "dateUpdated": "2026-10-30T22:48:09.173Z"}, "containers": {"cna": {"title": "secp256k1-native: Compiler-reconstructed secret-dependent branch in native scalar multiplication", "problemTypes": [{"descriptions": [{"cweId": "CWE-208", "lang": "en", "description": "CWE-208: Observable Timing Discrepancy", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-1255", "lang": "en", "description": "CWE-1255: Comparison Logic is Vulnerable to Power Side-Channel Attacks", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/sgbett/secp256k1-native/security/advisories/GHSA-vp2j-gqfm-r3cf", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/sgbett/secp256k1-native/security/advisories/GHSA-vp2j-gqfm-r3cf"}, {"name": "https://github.com/sgbett/secp256k1-native/pull/32", "tags": ["x_refsource_MISC"], "url": "https://github.com/sgbett/secp256k1-native/pull/32"}, {"name": "https://github.com/sgbett/secp256k1-native/commit/a89bea1617a2d063c6545ad44565dc22098c880e", "tags": ["x_refsource_MISC"], "url": "https://github.com/sgbett/secp256k1-native/commit/a89bea1617a2d063c6545ad44565dc22098c880e"}, {"name": "https://github.com/sgbett/secp256k1-native/blob/master/docs/advisories/0001-compiler-reconstructed-ct-branch.md", "tags": ["x_refsource_MISC"], "url": "https://github.com/sgbett/secp256k1-native/blob/master/docs/advisories/0001-compiler-reconstructed-ct-branch.md"}, {"name": "https://github.com/sgbett/secp256k1-native/releases/tag/v0.18.0", "tags": ["x_refsource_MISC"], "url": "https://github.com/sgbett/secp256k1-native/releases/tag/v0.18.0"}], "affected": [{"vendor": "sgbett", "product": "secp256k1-native", "versions": [{"version": ">= 0.17.0, < 0.18.0", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-10-30T22:48:09.173Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-vp2j-gqfm-r3cf", "discovery": "UNKNOWN"}}}}

{}

{"affected": [{"affectedData": [{"product": "secp256k1-native", "vendor": "sgbett", "versions": [{"status": "affected", "version": ">= 0.17.0, < 0.18.0"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-63410", "lastModified": "2026-10-30T23:17:15.547", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.9, "baseSeverity": "MEDIUM", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 3.6, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-10-30T23:17:15.547", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/sgbett/secp256k1-native/blob/master/docs/advisories/0001-compiler-reconstructed-ct-branch.md"}, {"source": "security-advisories@github.com", "url": "https://github.com/sgbett/secp256k1-native/commit/a89bea1617a2d063c6545ad44565dc22098c880e"}, {"source": "security-advisories@github.com", "url": "https://github.com/sgbett/secp256k1-native/pull/32"}, {"source": "security-advisories@github.com", "url": "https://github.com/sgbett/secp256k1-native/releases/tag/v0.18.0"}, {"source": "security-advisories@github.com", "url": "https://github.com/sgbett/secp256k1-native/security/advisories/GHSA-vp2j-gqfm-r3cf"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-208"}, {"lang": "en", "value": "CWE-1255"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"created": "2026-10-31T00:30:14.796346+00:00", "updated": "2026-10-31T00:30:14.796354+00:00", "vendors": []}