CVE-2026-98044

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the BPF (Berkeley Packet Filter) subsystem where the check ld abs() function models failed BPF LD ABS or BPF LD IND instructions in a subprogram as an implicit return with the R0 register set to zero. When this load is accessed directly from a synchronous callback, the prepare func exit() function enforces the callback return contract and marks R0 as precise. Because R0 is not derived from a real instruction on this path, precision backtracking triggers a verifier bug known as callback unexpected regs. Consequently, a privileged program loader can trigger a verifier warning and an -EFAULT BPF PROG LOAD error.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.