Summary
Blst vulnerable to incorrect results for some inputs in blstfpeucl_inverse function
Description
During the course of differential fuzzing of the blst library by @guidovranken it was discovered that blst would produce the incorrect result for some input values in the inverse function. This was the result of the introduction of a new inversion formula in version v0.3.0. This source of these incorrect outputs was due to two issues:
- The amount of inner loop iterations was not sufficient for the algorithm to converge.
- It was erroneously assumed that the absolute value of the intermediate result would be capped at 767-bits. As a result, some output values were truncated by one bit or the most significant bit was misinterpreted as the sign.
References
The software used to uncover this issue can be found here.
Credits
A special thanks to Guido Vranken (@guidovranken) for his discovery and disclosure of this vulnerability.
For more information
If you have any questions or comments about this advisory please email us at [email protected]
Impact
Blst versions v0.3.0 to v0.3.2 can produce the incorrect outputs for some inputs to the blst_fp_eucl_inverse function. This could theoretically result in the creation of an invalid signature from correct inputs. However, fuzzing of higher level functions such as sign and verify were unable to produce incorrect results and there has been no reported occurrences of this issue being encountered in production use.
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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This issue has been resolved in the v0.3.3 release and users are recommended to upgrade immediately.
Frequently Asked Questions
- What is GHSA-X279-68RR-JP4P? GHSA-X279-68RR-JP4P is a medium-severity security vulnerability in github.com/supranational/blst (go), affecting versions >= 0.3.0, < 0.3.3. It is fixed in 0.3.3.
- Which versions of github.com/supranational/blst are affected by GHSA-X279-68RR-JP4P? github.com/supranational/blst (go) versions >= 0.3.0, < 0.3.3 is affected.
- Is there a fix for GHSA-X279-68RR-JP4P? Yes. GHSA-X279-68RR-JP4P is fixed in 0.3.3. Upgrade to this version or later.
- Is GHSA-X279-68RR-JP4P exploitable, and should I be worried? Whether GHSA-X279-68RR-JP4P 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-X279-68RR-JP4P 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-X279-68RR-JP4P? Upgrade
github.com/supranational/blstto 0.3.3 or later.