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 H H 7.8 .0078 53.2 —
AFFECTED Product Versions Fixed Linux dff1399f8addf7129c49bb2227469da79cc30b47 – — Linux 3.17 – 4.4.296
TIMELINE May 22 Reserved by Linux May 24 Published (CNA: Linux) Aug 4 RESCORED — CVE-2021-47506 (Linux). CVSS 9.8 → 7.8 (NVD).
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix use-after-free due to delegation race A delegation break could arrive as soon as we've called vfs_setlease. A delegation break runs a callback which immediately (in nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we then exit nfs4_set_delegation without hashing the delegation, it will be freed as soon as the callback is done with it, without ever being removed from del_recall_lru. Symptoms show up later as use-after-free or list corruption warnings, usually in the laundromat thread. I suspect aba2072f4523 "nfsd: grant read delegations to clients holding writes" made this bug easier to hit, but I looked as far back as v3.0 and it looks to me it already had the same problem. So I'm not sure where the bug was introduced; it may have been there from the beginning.
| Date | Event | Detail |
|---|---|---|
| May 22, 2024 | Reserved | Reserved by Linux |
| May 24, 2024 | Published | Published (CNA: Linux) |
| August 4, 2026 | RESCORED | RESCORED — CVE-2021-47506 (Linux). CVSS 9.8 → 7.8 (NVD). |
Authoritative record: CVE-2021-47506 at cve.org
Vendors: linux
Weaknesses: CWE-416
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-47506 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.