CVE-2026-64114 Linux CVE debrief

Who should care

System administrators and users of Linux kernels should be aware of this vulnerability. An unprivileged process in a user+net namespace on a kernel with CONFIG_USER_NS=y can exploit this vulnerability. Linux kernel developers and maintainers should review the patch and ensure that it is properly integrated into the kernel codebase.

Technical summary

The Linux kernel's raw_send_hdrinc() function did not properly validate IPv4 headers with ihl < 5. This can lead to an out-of-bounds access when the packet is processed by downstream consumers, such as ah_output() in net/ipv4/ah4.c. The vulnerability can be triggered by a crafted packet with a malformed IPv4 header. The vulnerability affects Linux kernel versions and can be exploited by an unprivileged process in a user+net namespace on a kernel with CONFIG_USER_NS=y.

Defensive priority

High priority should be given to patching this vulnerability, as it can be exploited by an unprivileged process. The vulnerability has a high impact on system security and should be patched immediately.

Recommended defensive actions

• Apply the patch to update the Linux kernel
• Restrict CAP_NET_RAW to trusted users
• Monitor network traffic for suspicious packets
• Review system configurations to ensure that the vulnerable kernel version is not in use
• Perform a thorough review of network traffic logs to detect potential exploitation attempts
• Implement compensating controls, such as firewall rules, to limit the impact of the vulnerability
• Track exceptions and retest remediated assets to ensure that the vulnerability has been properly mitigated

Evidence notes

The CVE record was published on 2026-07-19T16:17:52.820Z and has not been modified since then. The NVD entry is currently Received. There is no additional information available about the vulnerability beyond what is provided in the CVE record and NVD entry. Further verification and review of system configurations and network traffic are necessary to determine the impact of this vulnerability.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.