{"cve":"CVE-2026-90234","nvd":{"published":"2026-09-17T17:17:19.293","modified":"2026-10-21T13:20:44.170","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: Return a delegation the client fails to record\n\nWhen an NFS server grants a delegation in an OPEN reply,\nnfs_inode_set_delegation() records it on the client. However, three\nof its error flows return without sending DELEGRETURN.\n\nA delegation can be relinquished only by DELEGRETURN (RFC 8881\nSection 20.2.4), so dropping one silently leaves the server believing\nthe client still holds it. If the server happens to recall that\ndelegation, the client answers CB_RECALL with NFS4ERR_BADHANDLE\nbecause it has no record of the stateid. The server revokes the\ndelegation and moves it onto its cl_revoked list, because the client\nnever sends the FREE_STATEID that would drain it. Every subsequent\nSEQUENCE reply then carries SEQ4_STATUS_RECALLABLE_STATE_REVOKED,\nand the client's state manager loops issuing TEST_STATEID across its\ndelegations without ever clearing the condition.\n\nThe window is easy to reach now that a server offers a write\ndelegation on any write OPEN: a delegation recalled for one opener\nraces a re-open that the server answers with a fresh write\ndelegation.\n\nInstead of dropping it, hand the delegation back during these error\nflows.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":[],"references":["https://git.kernel.org/stable/c/220af23d863995091f0edeb1e6aa0945b3db8b37","https://git.kernel.org/stable/c/6822ba1ae9b6df6a094f7f8998f1da734c85fa19","https://git.kernel.org/stable/c/92533e49fe3c455088657b862cf3562260c0ce25","https://git.kernel.org/stable/c/9e71e332fa2c7a48f3d00001f856a13cc2d69639","https://git.kernel.org/stable/c/fe3b1c8966a27b70599d28ce7e80819adac1ff22"],"products":[],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-90234","score":0.0063,"percentile":0.49875,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}