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CVE-2026-39457 is a stack-based buffer overflow in FreeBSD's libnv. When exchanging data over a socket, libnv uses select(2) to wait for data, but does not verify that the supplied socket descriptor is within select(2)'s fd_set size limit, FD_SETSIZE (1024). If libnv is given a file descriptor greater than or equal to FD_SETSIZE, the descriptor can overflow the fixed-size fd_set used by select-related macros, resulting in stack corruption. The issue is locally triggerable by an attacker who can cause a libnv-consuming application to operate on unusually large file descriptors, for example by exhausting lower-numbered descriptors before execing a target program that fails to close inherited descriptors. In privileged consumers, including setuid-root programs, this memory corruption can be leveraged for local privilege escalation.
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6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
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