CVE-2025-39688

Status: ModifiedMedium (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

nfsd: allow SC_STATUS_FREEABLE when searching via nfs4_lookup_stateid()

The pynfs DELEG8 test fails when run against nfsd. It acquires a delegation and then lets the lease time out. It then tries to use the deleg stateid and expects to see NFS4ERR_DELEG_REVOKED, but it gets bad NFS4ERR_BAD_STATEID instead.

When a delegation is revoked, it's initially marked with SC_STATUS_REVOKED, or SC_STATUS_ADMIN_REVOKED and later, it's marked with the SC_STATUS_FREEABLE flag, which denotes that it is waiting for s FREE_STATEID call.

nfs4_lookup_stateid() accepts a statusmask that includes the status flags that a found stateid is allowed to have. Currently, that mask never includes SC_STATUS_FREEABLE, which means that revoked delegations are (almost) never found.

Read full descriptionShow less

Add SC_STATUS_FREEABLE to the always-allowed status flags, and remove it from nfsd4_delegreturn() since it's now always implied.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Base score: 5.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.61%
Percentile among all scored CVEs: 47
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Linux — Linux Kernel

CWEs

NVD-CWE-noinfo

References

Raw JSON (NVD)

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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: allow SC_STATUS_FREEABLE when searching via nfs4_lookup_stateid()\n\nThe pynfs DELEG8 test fails when run against nfsd. It acquires a\ndelegation and then lets the lease time out. It then tries to use the\ndeleg stateid and expects to see NFS4ERR_DELEG_REVOKED, but it gets\nbad NFS4ERR_BAD_STATEID instead.\n\nWhen a delegation is revoked, it's initially marked with\nSC_STATUS_REVOKED, or SC_STATUS_ADMIN_REVOKED and later, it's marked\nwith the SC_STATUS_FREEABLE flag, which denotes that it is waiting for\ns FREE_STATEID call.\n\nnfs4_lookup_stateid() accepts a statusmask that includes the status\nflags that a found stateid is allowed to have. Currently, that mask\nnever includes SC_STATUS_FREEABLE, which means that revoked delegations\nare (almost) never found.\n\nAdd SC_STATUS_FREEABLE to the always-allowed status flags, and remove it\nfrom nfsd4_delegreturn() since it's now always implied."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nfsd: permite SC_STATUS_FREEABLE al buscar mediante nfs4_lookup_stateid() La prueba pynfs DELEG8 falla cuando se ejecuta contra nfsd. Adquiere una delegación y luego deja que se agote el tiempo de concesión. Luego intenta usar el stateid de la deleg y espera ver NFS4ERR_DELEG_REVOKED, pero en su lugar obtiene NFS4ERR_BAD_STATEID incorrecto. Cuando se revoca una delegación, inicialmente se marca con SC_STATUS_REVOKED o SC_STATUS_ADMIN_REVOKED y, más tarde, se marca con el indicador SC_STATUS_FREEABLE, que indica que está esperando una llamada FREE_STATEID. nfs4_lookup_stateid() acepta una máscara de estado que incluye los indicadores de estado que se permite que tenga un stateid encontrado. Actualmente, esa máscara nunca incluye SC_STATUS_FREEABLE, lo que significa que las delegaciones revocadas (casi) nunca se encuentran. Agregue SC_STATUS_FREEABLE a los indicadores de estado siempre permitidos y elimínelo de nfsd4_delegreturn(), ya que ahora siempre está implícito."
    }
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  "lastModified": "2026-07-30T06:23:40.040",
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