Summary
Blst has logical error in SigValidate in Go bindings
Description
The vulnerable function is declared as SigValidate(sigInfcheck bool) bool and if called with sigInfcheck argument set to true, the group-check was omitted. The group-check is required to be performed on untrusted input, because the pairing, the corner-stone operation of the signature scheme, is defined only on points that are members of a specific cyclic group, which is a subset of all the possible points on elliptic curves in question. Submitting an untrusted point outside the group opens up the possibility of accepting an alternative signature for a chosen message.
It should be noted that the SigValidate call is not the only way to perform the group-checks. There are optional checks integrated into various other verification methods, such as Verify, AggregateVerify, etc., as well as signature aggregation methods, such as PairingAggregate*. The reason why there are multiple options is that the group-check is a relatively expensive operation, and application developers are arguably entitled the freedom to choose when it's performed.
Credits
A special thanks to Yunjong Jeong (@blukat29) for the discovery and disclosure of this vulnerability.
Impact
Blst versions v0.3.0 through 0.3.10 failed to perform a signature group-check if the call to SigValidate in the Go bindings was complemented with a check for infinity. Formally speaking, infinity, or the identity element of the elliptic curve group, is a member of the group, and the group-check should allow it. An initial review of blst users on GitHub did not uncover any use of this function with the complementary infinity check. This optional check was added as a convenience feature because despite infinity being a legitimate member of the group, individual signatures should never be infinite (as it is equivalent to having zero for the secret key), and observing one should raise a flag.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
This issue has been resolved in the v0.3.11 release and users are advised to update if their application is affected or alternatively omit the complementary infinity check.
Frequently Asked Questions
- What is GHSA-8C37-7QX3-4C4P? GHSA-8C37-7QX3-4C4P is a medium-severity security vulnerability in github.com/supranational/blst (go), affecting versions >= 0.3.0, < 0.3.11. It is fixed in 0.3.11.
- Which versions of github.com/supranational/blst are affected by GHSA-8C37-7QX3-4C4P? github.com/supranational/blst (go) versions >= 0.3.0, < 0.3.11 is affected.
- Is there a fix for GHSA-8C37-7QX3-4C4P? Yes. GHSA-8C37-7QX3-4C4P is fixed in 0.3.11. Upgrade to this version or later.
- Is GHSA-8C37-7QX3-4C4P exploitable, and should I be worried? Whether GHSA-8C37-7QX3-4C4P is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-8C37-7QX3-4C4P is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-8C37-7QX3-4C4P? Upgrade
github.com/supranational/blstto 0.3.11 or later.