CVE-2026-74563 Linux CVE debrief

Who should care

Linux system administrators and security teams should assess exposure, particularly for systems using RDS TCP. Those with Linux kernel versions prior to the fixed versions should prioritize patching or updating.

Why it matters

CVE-2026-74563 is a use-after-free vulnerability in the Linux kernel's RDS TCP module. It allows for potential exploitation leading to reading freed memory, which could result in various impacts including information disclosure or system crashes. Linux system administrators and security teams should assess exposure, particularly for systems using RDS TCP, and prioritize patching or updating affected systems.

• Verify and apply patches or updates to mitigate the vulnerability.
• Review network configurations to minimize exposure.
• Monitor system logs for potential exploitation attempts.

Technical summary

The Linux kernel's RDS TCP module has a use-after-free vulnerability. In the `rds_tcp_laddr_check()` function, the RCU lock is dropped after looking up a scoped IPv6 interface with `dev_get_by_index_rcu()`, but before passing the `struct net_device *` to `ipv6_chk_addr()`. This allows a concurrent RTM_DELLINK operation to free the `net_device`, leading to a use-after-free error when `ipv6_chk_addr()` accesses the freed memory.

Defensive priority

Apply patches or updates from the Linux vendor to affected systems, particularly those using RDS TCP.

Recommended defensive actions

• Apply patches or updates from the Linux vendor to affected systems, particularly those using RDS TCP.
• Review and update affected Linux systems' network configurations to minimize exposure.
• Monitor system logs for potential exploitation attempts.
• Verify whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record and Linux kernel source code indicate a use-after-free vulnerability in RDS TCP. Specific commits fixing the issue are provided. The vulnerability allows for potential exploitation leading to reading freed memory, which could result in various impacts including information disclosure or system crashes. The fix involves holding the RCU read-side lock across the ipv6_chk_addr() call to prevent the device from being freed while it is in use. Evidence limits are based on available details from the CVE record and Linux The

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.