CVE-2024-26845 is a vulnerability in the Linux kernel's SCSI target core subsystem, specifically related to the handling of Task Management Functions (TMF) in the tmr_list. The issue arises because abort commands that are responded to by the iSCSI layer itself are added to the tmr_list but are not properly forwarded to the target core. When a LUN_RESET TMF is processed through the tmr_list, it takes a reference counter on the abort and waits for its completion. However, since the abort was never initiated in the target core, it never completes, causing the waiting process to hang indefinitely. This results in kernel worker threads being blocked for extended periods, as evidenced by logs showing tasks stuck for hundreds of seconds. The root cause is that aborts are added to the tmr_list without ensuring they will be handled by the target core, leading to a deadlock scenario. The fix involves modifying the kernel code to add aborts to the tmr_list only if they will be processed by the target core, preventing indefinite blocking. This vulnerability affects Linux kernel versions identified by the given commit hashes, and it impacts systems using the SCSI target functionality, particularly those leveraging iSCSI for storage networking. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-26845 can be significant, especially for enterprises and data centers relying on Linux-based storage servers or SAN (Storage Area Network) infrastructure using iSCSI targets. The vulnerability can cause kernel worker threads to become indefinitely blocked, leading to degraded system performance, potential denial of service (DoS), and disruption of storage operations. This can affect critical applications dependent on reliable storage access, including cloud services, financial systems, telecommunications, and industrial control systems. The inability to complete TMF commands properly may result in stalled I/O operations, impacting data availability and potentially causing cascading failures in storage-dependent services. Although the vulnerability does not appear to allow direct code execution or privilege escalation, the denial of service impact on storage targets can have severe operational consequences. European organizations with high reliance on Linux storage servers or virtualization platforms using iSCSI targets are particularly at risk. The absence of known exploits reduces immediate threat but does not eliminate risk, especially if attackers develop targeted exploits to cause service disruption.

To mitigate CVE-2024-26845, European organizations should: 1) Apply the latest Linux kernel patches that address this vulnerability as soon as they become available from trusted Linux distributions or kernel maintainers. 2) Audit and monitor systems running SCSI target services, particularly those using iSCSI, for signs of blocked kernel worker threads or unusual storage delays. 3) Implement proactive kernel and system monitoring to detect long-running or stuck kernel tasks related to target_core_mod workqueues. 4) Where possible, isolate critical storage target servers and limit access to trusted networks to reduce exposure to malicious TMF commands. 5) Consider temporary workarounds such as disabling iSCSI target functionality if it is not essential, until patches are applied. 6) Maintain up-to-date backups and disaster recovery plans to mitigate potential service disruptions caused by this vulnerability. 7) Engage with Linux distribution vendors and security mailing lists to track patch releases and advisories related to this CVE.