Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
AV AC PR UI S C I A CVSS EPSS %ile KEV L L L N U H N H 7.1 .0028 20.9 —
AFFECTED Product Versions Fixed Linux 4a4eeefa514db570be025ab46d779af180e2c9bb – — Linux 6.11 – 5.4.291
TIMELINE Dec 29 Reserved by Linux Jan 19 Published (CNA: Linux) Jul 30 RESCORED — CVE-2025-21647 (Linux). CVSS 7.3 → 7.1 (NVD).
In the Linux kernel, the following vulnerability has been resolved: sched: sch_cake: add bounds checks to host bulk flow fairness counts Even though we fixed a logic error in the commit cited below, syzbot still managed to trigger an underflow of the per-host bulk flow counters, leading to an out of bounds memory access. To avoid any such logic errors causing out of bounds memory accesses, this commit factors out all accesses to the per-host bulk flow counters to a series of helpers that perform bounds-checking before any increments and decrements. This also has the benefit of improving readability by moving the conditional checks for the flow mode into these helpers, instead of having them spread out throughout the code (which was the cause of the original logic error). As part of this change, the flow quantum calculation is consolidated into a helper function, which means that the dithering applied to the ost load scaling is now applied both in the DRR rotation and when a sparse flow's quantum is first initiated. The only user-visible effect of this is that the maximum packet size that can be sent while a flow stays sparse will now vary with +/- one byte in some cases. This should not make a noticeable difference in practice, and thus it's not worth complicating the code to preserve the old behaviour.
| Date | Event | Detail |
|---|---|---|
| December 29, 2024 | Reserved | Reserved by Linux |
| January 19, 2025 | Published | Published (CNA: Linux) |
| July 30, 2026 | RESCORED | RESCORED — CVE-2025-21647 (Linux). CVSS 7.3 → 7.1 (NVD). |
Authoritative record: CVE-2025-21647 at cve.org
Vendors: linux
Weaknesses: CWE-125
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2025-21647 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.