CVE-2026-63889
HighCVSS 8.1Exploitation Probability (EPSS)
Low risk26th percentile - higher than 26% of all known CVEs
Summary
A vulnerability in the Linux kernel's SCSI Fibre Channel (FC) transport subsystem allows an attacker with FC fabric access to send a crafted FPIN ELS frame, causing an infinite loop in the FC transport driver and resulting in a denial of service (DoS). The issue stems from using an 8-bit counter for a 32-bit pname_count field, which wraps at 256 and keeps the loop condition true indefinitely.
Risk Assessment
The organization is at risk of a DoS attack from the Fibre Channel network, potentially crashing Linux initiators (e.g., lpfc, qla2xxx) and disrupting storage access. The attack requires FC fabric access, such as through a compromised switch or fabric controller.
Recommendation
Apply the Linux kernel patch addressing CVE-2026-63889 immediately. Update to a kernel version containing the commit that widens the counter to u32 and clamps pname_count.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS frame to an lpfc or qla2xxx Linux initiator can trigger a non-return in the generic FC transport. This is not a local userspace or IP network path; the attacker must be able to inject fabric traffic, for example as a compromised switch or fabric controller, or as a same-zone N_Port on a fabric that permits source spoofing. The Link-Integrity and Peer-Congestion FPIN walkers used a u8 loop counter against the 32-bit on-wire pname_count field, and did not bound pname_count by the descriptor body already validated by the TLV walker. A pname_count of 256 therefore wraps the counter and keeps the loop condition true indefinitely. Factor the shared pname_list[] walk into one helper, widen the counter to u32, and clamp pname_count against the entries that fit in the descriptor body before iterating.