A truncation error in the Linux netfilter rate estimator caused the local variables in xt_rateest_mt() to be stored as 32‑bit integers when they should have been 64‑bit. On network interfaces that operate at speeds above about 34 Gb/s, the byte rate can exceed 2^32‑1 (~4.3 GB/s). The truncated value therefore becomes incorrect, which means that the estimator’s comparison no longer reflects the true traffic rate. An attacker or rogue host could exploit this by sending traffic that is misclassified, thereby bypassing rate limiting or, conversely, causing legitimate traffic to be unduly throttled, resulting in a denial of service to users on that link.

All Linux kernel releases are affected until the patch that changes the local variables to u64 is applied. The vulnerability is present in the core kernel netfilter code, affecting every distribution that uses the upstream kernel source. No specific version range is listed, so it is prudent to consider all kernels prior to the patch as vulnerable.

The vulnerability involves kernel code and can affect the entire system’s traffic handling, giving it a medium severity (CVSS score 5.5) with potential impacts on confidentiality, integrity, and availability. The likely attack vector would involve a host with network access to the affected interface, but this is inferred from the nature of the netfilter component and not explicitly stated in the CVE data. While no publicly documented exploits exist at the time of this analysis, the EPSS score of <1% indicates a very low probability of exploitation. The KEV catalog does not list this issue, suggesting that it is not a known exploited vulnerability yet. Nevertheless, the combination of medium severity and possible remote trigger warrants a strong remediation posture.