VulnerabilityPublished 30 Oct 2026

CVE-2026-63410: sgbett secp256k1-native · Timing Side Channel

Affects sgbett secp256k1-nativeSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 0.18.0 when convenient.

Data as of 30 Oct 2026, 23:12 UTC

CVSS 3.1 base score

5.9Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	5.9

Patch: Available – fixed in 0.18.0

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade sgbett secp256k1-native to 0.18.0.

Affected software

Product	Affected	Fixed in
sgbettsecp256k1-native	Affected >=0.17.0 <0.18.0	Fixed in 0.18.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade secp256k1-native to version 0.18.0 or later, which contains the verified fix for this timing leak. Users compiling the library with affected GCC versions should ensure they use the fixed version. The pure-Ruby implementation path is not affected. No additional mitigations are indicated by the vendor advisory.

Description

CVE-2026-63410 is a timing side-channel vulnerability in the secp256k1-native library version 0.17.0 up to but not including 0.18.0. The issue arises from native constant-time scalar multiplication functions compiled with certain GCC versions at optimization level -O2, which reconstruct branchless selection into secret-dependent branches. This leaks timing information about secret scalars, potentially allowing attackers to statistically recover bits of private keys or nonces through repeated timing measurements. The vulnerability is fixed in version 0.18.0.

Impact

An attacker capable of observing timing measurements of scalar multiplication operations can statistically infer bits of secret scalars such as private keys or nonces. This compromises the confidentiality of cryptographic secrets, potentially undermining the security of cryptographic operations relying on secp256k1-native in affected versions. There is no indication of integrity or availability impact. No known exploits are reported in the wild.

Summary

The secp256k1-native library for Ruby implements native constant-time scalar multiplication using the Montgomery ladder algorithm. However, when compiled with GCC versions 14.3.0, 15.1.0, and 15.2.0 at -O2 optimization, the compiler reconstructs branchless selection code into conditional jumps dependent on secret scalar bits. This breaks the constant-time assumption and leaks timing information that can be exploited to recover secret scalar bits. Earlier GCC versions and the pure-Ruby implementation do not exhibit this flaw. The issue is resolved in version 0.18.0 of the library.

CWE-208Observable Timing Discrepancy (opens in a new tab)
Base weakness
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Cross-Domain Search Timing (opens in a new tab)
Application Fingerprinting (opens in a new tab)
System Footprinting (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1255Comparison Logic is Vulnerable to Power Side-Channel Attacks (opens in a new tab)
Variant weakness
A device's real time power consumption may be monitored during security token evaluation and the information gleaned may be used to determine the value of the reference token.
Architecture and Design
The design phase must consider each check of a security token against a standard and the amount of power consumed during the check of a good token versus a bad token. The alternative is an all at once check where a retry counter is incremented PRIOR to the check.
Architecture and Design
Another potential mitigation is to parallelize shifting of secret data (see example 2 below). Note that the wider the bus the more effective the result.
Architecture and Design
An additional potential mitigation is to add random data to each crypto operation then subtract it out afterwards. This is highly effective but costly in performance, area, and power consumption. It also requires a random number generator.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Black Box Reverse Engineering (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 23:12 UTC

WeaknessesCWE-208, CWE-1255

Technical details

References

Community reviews

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