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CVE-2025-21648 is an input-validation flaw in the Linux kernel netfilter conntrack subsystem. The maximum conntrack hashtable size was not clamped to INT_MAX during resizing. An oversized resize request can reach __kvmalloc_node_noprof() without __GFP_NOWARN set and trigger WARN_ON_ONCE. Conntrack hashtable resizing is possible only from the initial network namespace (init_netns).
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Linux kernel netfilter conntrack hashtable-size validation flaw.
A Linux kernel Netfilter connection-tracking vulnerability involving an insufficient maximum bound on conntrack hashtable resizing. An oversized allocation can trigger a kernel WARN condition; resizing is restricted to the initial network namespace.
A Linux kernel netfilter connection-tracking issue in which an oversized conntrack hash-table resize can trigger a WARN_ON_ONCE condition during memory allocation. The fix clamps the maximum conntrack hashtable size to INT_MAX. The referenced Google COS kernel packages are affected.
A Linux kernel netfilter conntrack vulnerability involving clamping the maximum hashtable size to INT_MAX, addressed in this Red Hat kernel security update.
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