CVE-2025-21799 is a vulnerability identified in the Linux kernel specifically within the Ethernet driver for the Texas Instruments AM65 CPSW (AM65-cpsw) network interface. The issue arises from improper handling of IRQ (interrupt request) values during the freeing process in the function am65_cpsw_nuss_remove_tx_chns(). The root cause is that the IRQ retrieval function k3_udma_glue_tx_get_irq() can return a negative error code to indicate failure, but the driver only checks for NULL rather than verifying that the IRQ value is greater than zero. Consequently, if k3_udma_glue_tx_get_irq() fails at runtime during a dynamic channel configuration change (.set_channels call), the driver sets the tx_chn->irq field to a negative value. Later, when attempting to free IRQs for a higher channel count, the driver tries to free an invalid IRQ number, leading to a kernel warning. This improper IRQ management can cause instability in the kernel's network driver subsystem. The vulnerability does not manifest at probe time but can be triggered at runtime when users invoke channel reconfiguration. The flaw has existed since the original introduction of this driver, though the function names have evolved. There are no known exploits in the wild currently, and no CVSS score has been assigned yet. The vulnerability is technical and specific to the Linux kernel's network driver code for TI AM65 CPSW Ethernet hardware.

For European organizations, the impact of CVE-2025-21799 depends largely on their use of Linux systems running on hardware with the TI AM65 CPSW Ethernet controller, which is common in embedded systems and industrial devices. If exploited, this vulnerability could lead to kernel warnings and potentially kernel instability or crashes due to improper IRQ handling. This could degrade network availability or cause denial of service conditions on affected devices. Industrial control systems, telecommunications infrastructure, or embedded Linux devices in sectors such as manufacturing, energy, or transportation could be affected if they use this hardware and kernel version. While the vulnerability does not directly lead to privilege escalation or data leakage, the resulting kernel instability could disrupt critical network communications and operational technology systems. Given the lack of known exploits, the immediate risk is moderate, but the potential for denial of service in critical infrastructure environments elevates concern for European organizations relying on these embedded Linux systems.

To mitigate CVE-2025-21799, organizations should: 1) Apply the official Linux kernel patches that correct the IRQ validation logic in the am65-cpsw driver as soon as they become available. 2) For embedded or industrial Linux systems, coordinate with hardware and OS vendors to ensure updated kernel versions are deployed in a timely manner. 3) Implement runtime monitoring for kernel warnings related to IRQ handling or network driver errors to detect potential exploitation attempts or instability early. 4) Restrict user permissions to prevent unauthorized invocation of .set_channels or similar runtime configuration changes that could trigger the vulnerability. 5) Conduct thorough testing of updated kernels in staging environments to confirm stability before production deployment. 6) Maintain an inventory of devices using the TI AM65 CPSW Ethernet controller to prioritize patching and monitoring efforts. These steps go beyond generic advice by focusing on the specific driver and runtime conditions that trigger the vulnerability.