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CVE-2025-21647 is an out-of-bounds memory-access vulnerability in the Linux kernel CAKE traffic-control scheduler, sch_cake. A logic condition can underflow per-host bulk-flow fairness counters; subsequent use of the invalid counter state can access memory outside the intended bounds. The condition was triggered by syzbot after an earlier related logic-error correction. The upstream correction centralizes counter updates in helpers that validate bounds before increments and decrements and moves flow-mode checks into those helpers.
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6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Linux kernel vulnerability in sched/sch_cake related to missing bounds checks on host bulk flow fairness counts.
Linux kernel CAKE scheduler bounds-checking vulnerability.
Linux kernel sch_cake bounds-checking flaw.
A Linux kernel sch_cake scheduler vulnerability in which an underflow of per-host bulk-flow fairness counters can cause an out-of-bounds memory access. The fix centralizes counter accesses in bounds-checking helper functions.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.