CVE-2026-52921
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk6th percentile — higher than 6% of all known CVEs
Summary
In the Linux kernel netfilter/ipset subsystem, a vulnerability was found in several hash:* variants. The 32-bit iterator used for scanning IPv4 address ranges may advance past the requested range after completion, causing retries to start from an unintended position.
Risk Assessment
The organization may experience incorrect behavior of ipset-based firewall rules, potentially bypassing intended access restrictions or causing erroneous network traffic processing.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit in the netfilter branch) and reboot or load the new kernel.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: stop hash:* range iteration at end The following hash set variants: hash:ip,mark hash:ip,port hash:ip,port,ip hash:ip,port,net iterate IPv4 ranges with a 32-bit iterator. The iterator must stop once the last address in the requested range has been processed. Advancing it once more can move the traversal state past the end of the request, so a later retry may continue from an unintended position. Handle the iterator increment explicitly at the end of the loop and stop once the upper bound has been processed. This keeps the existing retry behaviour intact for valid ranges while preventing traversal from continuing past the original boundary.