Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state… (CVE-2025-21795)
In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state then there is no point to send the callback. This causes nfsd4_shutdown_callback to hang since cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP notifies NFSD that the connection was dropped. This patch modifies nfsd4_run_cb_work to skip the RPC call if nfs4_client is in courtesy state.
AI Analysis
Technical Summary
This Red Hat security advisory (RHSA-2026:0804) addresses six distinct vulnerabilities in the Linux kernel packages for Red Hat Enterprise Linux 9.6 Extended Update Support. The fixed issues include: a hang in nfsd4_shutdown_callback (CVE-2025-21795), teardown of vGIC on failed vCPU creation in KVM arm64 (CVE-2025-37849), a buffer overflow in ALSA via malformed UMP SysEx messages (CVE-2025-37891), a race condition when updating an existing NFS write (CVE-2025-39697), an invalid quirk input mapping in Intel bytcr_rt5640 ASoC driver (CVE-2025-40154), and a potential use-after-free in libceph (CVE-2025-68285). Red Hat has released updated kernel packages that fix these vulnerabilities and requires a system reboot for the update to take effect.
Potential Impact
The vulnerabilities collectively affect the Linux kernel core components and drivers, potentially causing system hangs, memory corruption, race conditions, and use-after-free scenarios. These issues could impact system stability and security on affected Red Hat Enterprise Linux 9.6 systems. The advisory rates the overall security impact as Important (high severity). There are no known exploits in the wild at the time of this advisory.
Mitigation Recommendations
Red Hat has released updated kernel packages that address these vulnerabilities. Users of Red Hat Enterprise Linux 9.6 Extended Update Support should apply the provided kernel update and reboot their systems to ensure the fixes take effect. For detailed update instructions, refer to https://access.redhat.com/articles/11258. No additional mitigations are indicated by the vendor advisory.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state… (CVE-2025-21795)
Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state then there is no point to send the callback. This causes nfsd4_shutdown_callback to hang since cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP notifies NFSD that the connection was dropped. This patch modifies nfsd4_run_cb_work to skip the RPC call if nfs4_client is in courtesy state.
CVSS v3.1
Score 7.5high
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This Red Hat security advisory (RHSA-2026:0804) addresses six distinct vulnerabilities in the Linux kernel packages for Red Hat Enterprise Linux 9.6 Extended Update Support. The fixed issues include: a hang in nfsd4_shutdown_callback (CVE-2025-21795), teardown of vGIC on failed vCPU creation in KVM arm64 (CVE-2025-37849), a buffer overflow in ALSA via malformed UMP SysEx messages (CVE-2025-37891), a race condition when updating an existing NFS write (CVE-2025-39697), an invalid quirk input mapping in Intel bytcr_rt5640 ASoC driver (CVE-2025-40154), and a potential use-after-free in libceph (CVE-2025-68285). Red Hat has released updated kernel packages that fix these vulnerabilities and requires a system reboot for the update to take effect.
Potential Impact
The vulnerabilities collectively affect the Linux kernel core components and drivers, potentially causing system hangs, memory corruption, race conditions, and use-after-free scenarios. These issues could impact system stability and security on affected Red Hat Enterprise Linux 9.6 systems. The advisory rates the overall security impact as Important (high severity). There are no known exploits in the wild at the time of this advisory.
Mitigation Recommendations
Red Hat has released updated kernel packages that address these vulnerabilities. Users of Red Hat Enterprise Linux 9.6 Extended Update Support should apply the provided kernel update and reboot their systems to ensure the fixes take effect. For detailed update instructions, refer to https://access.redhat.com/articles/11258. No additional mitigations are indicated by the vendor advisory.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2026:0804
- Cve Count
- 6
- Additional Cves
- ["CVE-2025-37849","CVE-2025-37891","CVE-2025-39697","CVE-2025-40154","CVE-2025-68285"]
Threat ID: 6a3da1ca4853345fc1821f9f
Added to database: 06/25/2026, 21:46:50 UTC
Last enriched: 06/25/2026, 22:02:13 UTC
Last updated: 09/10/2026, 19:24:55 UTC
Views: 55
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