# CVE-2026-99288: Linux kernel null pointer dereference in TCP established lookup

Source: https://junglewise.ai/threats/cve-2026-99288-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-99288 · Severity: info · Published 2026-11-10

The Linux kernel's TCP connection lookup mechanism could crash when processing certain network packets due to unsafe memory reuse patterns. An attacker on the network could cause a kernel panic, disrupting system availability and potentially forcing a reboot.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99288 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99288 being exploited in the wild.

**How severe is CVE-2026-99288?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** Linux Kernel before fix.

**Is there a fix for CVE-2026-99288?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-99288 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-99288?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in inet_lookup_established() and inet6_lookup_established() functions which perform lockless lookups using SLAB_TYPESAFE_BY_RCU allocated sockets. Memory reuse before RCU readers finish can lead to dereferencing unhashed sockets, causing a null pointer dereference when the code accesses sk_state through a NULL listener in tcp_v4_rcv(). The fix adds validation to check whether the nulls node is hashed after taking a reference and before returning the socket.

## Affected products

- Linux Linux kernel before fix

## Timeline

- 2026-11-10: disclosed

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