CVE-2025-22025
NoneCVSS
—
EPSS
0.6%
Published
Apr 16, 2025
CISA due date
—
Cloudanix analysis
A flaw in the Linux kernel's network file sharing code can slowly leak memory and eventually slow down or destabilize servers that handle file access requests.
- Exploitation
- Remote Authenticated
- Attacker needs
- Low Privilege
- Complexity
- Moderate
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Memory Corruption
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Unbalanced reference count increment on dl_stid before nfsd4_run_cb call is not decremented on queue failure, causing nfs4_stid object leaks in the NFS server delegation recall path.
Why it matters to the business
Gradual memory exhaustion on NFS servers can degrade performance or trigger instability after prolonged operation, especially in environments with frequent delegation activity.
How an attack unfolds
An attacker performs NFS open operations that allocate delegations and trigger recall callbacks; when nfsd4_run_cb fails to queue the work item the reference is leaked, allowing repeated triggering to accumulate unreferenced objects.
How to fix it
Update Linux kernel to commit b874cdef4e67e5150e07eff0eae1cbb21fb92da1 or later; apply the corresponding fixed package versions for affected distributions such as python3 and python3-libs on Red Hat rhel_aus:7.7.
How to confirm the fix worked
Verify kernel source contains the nfsd4_run_cb result check and nfs4_put_stid fallback; monitor for absence of the described kmem_cache_alloc backtraces under nfsd after patching.
Typical attack path
- Connect to NFS server and open files to obtain delegations
- Trigger delegation recall conditions via conflicting access
- Force nfsd4_run_cb to fail during dl_recall queuing
- Repeat to accumulate leaked nfs4_stid structures
How to detect it
Inspect kernel logs and slab allocator traces for repeated nfsd4_process_open and nfs4_alloc_stid backtraces without corresponding put operations; correlate with nfsd process memory growth over time.
What your security team should do
- Apply the referenced kernel commit or distribution updates immediately on all NFS servers
- Audit systems for signs of elevated nfsd memory consumption
- Prioritize patching given 560 days since publication and presence of similar privilege-escalation patterns in related kernel CVEs
The record
In the Linux kernel, the following vulnerability has been resolved: nfsd: put dl_stid if fail to queue dl_recall Before calling nfsd4_run_cb to queue dl_recall to the callback_wq, we increment the reference count of dl_stid. We expect that after the corresponding work_struct is processed, the reference count of dl_stid will be decremented through the callback function nfsd4_cb_recall_release. However, if the call to nfsd4_run_cb fails, the incremented reference count of dl_stid will not be decremented correspondingly, leading to the following nfs4_stid leak: unreferenced object 0xffff88812067b578 (size 344): comm "nfsd", pid 2761, jiffies 4295044002 (age 5541.241s) hex dump (first 32 bytes): 01 00 00 00 6b 6b 6b 6b b8 02 c0 e2 81 88 ff ff ....kkkk........ 00 6b 6b 6b 6b 6b 6b 6b 00 00 00 00 ad 4e ad de .kkkkkkk.....N.. backtrace: kmem_cache_alloc+0x4b9/0x700 nfsd4_process_open1+0x34/0x300 nfsd4_open+0x2d1/0x9d0 nfsd4_proc_compound+0x7a2/0xe30 nfsd_dispatch+0x241/0x3e0 svc_process_common+0x5d3/0xcc0 svc_process+0x2a3/0x320 nfsd+0x180/0x2e0 kthread+0x199/0x1d0 ret_from_fork+0x30/0x50 ret_from_fork_asm+0x1b/0x30 unreferenced object 0xffff8881499f4d28 (size 368): comm "nfsd", pid 2761, jiffies 4295044005 (age 5541.239s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 30 4d 9f 49 81 88 ff ff ........0M.I.... 30 4d 9f 49 81 88 ff ff 20 00 00 00 01 00 00 00 0M.I.... ....... backtrace: kmem_cache_alloc+0x4b9/0x700 nfs4_alloc_stid+0x29/0x210 alloc_init_deleg+0x92/0x2e0 nfs4_set_delegation+0x284/0xc00 nfs4_open_delegation+0x216/0x3f0 nfsd4_process_open2+0x2b3/0xee0 nfsd4_open+0x770/0x9d0 nfsd4_proc_compound+0x7a2/0xe30 nfsd_dispatch+0x241/0x3e0 svc_process_common+0x5d3/0xcc0 svc_process+0x2a3/0x320 nfsd+0x180/0x2e0 kthread+0x199/0x1d0 ret_from_fork+0x30/0x50 ret_from_fork_asm+0x1b/0x30 Fix it by checking the result of nfsd4_run_cb and call nfs4_put_stid if fail to queue dl_recall.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Debian:11 | linux | 0 | No fix |
| Debian:11 | linux-6.1 | 0 | 6.1.137-1~deb11u1 |
| Debian:12 | linux | 0 | No fix |
| Debian:13 | linux | 0 | No fix |
| Debian:13 | linux | 0 | 6.12.25-1 |
| Linux | Kernel | 0 | 5.10.236 |
| Linux | Kernel | 2.6.35 | 5.10.236 |
| Mageia:9 | kernel | 0 | 6.6.88-3.mga9 |
| Mageia:9 | kernel-linus | 0 | 6.6.88-1.mga9 |
| Mageia:9 | kmod-virtualbox | 0 | 7.0.24-70.mga9 |
| Mageia:9 | kmod-xtables-addons | 0 | 3.24-78.mga9 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP7 | kernel-default | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kernel-default | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Live Patching 12 SP5 | kgraft-patch-SLE12-SP5_Update_69 | 0 | 1-8.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6-RT_Update_11 | 0 | 1-150600.1.3.2 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_11 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-default | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_1 | 0 | 1-150700.15.3.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-64kb | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.50.1.150600.12.22.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-64kb | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-default | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-default-base | 0 | 6.4.0-150700.53.3.1.150700.17.2.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-source | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP7 | kernel-zfcpdump | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-coco | 0 | 6.4.0-15061.21.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-coco_debug | 0 | 6.4.0-15061.21.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-source-coco | 0 | 6.4.0-15061.21.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Confidential Computing Technical Preview 15 SP6 | kernel-syms-coco | 0 | 6.4.0-15061.21.coco15sp6.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | kernel-docs | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | kernel-obs-build | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | kernel-source | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Development Tools 15 SP7 | kernel-syms | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Module for Legacy 15 SP7 | kernel-default | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-azure | 0 | 6.4.0-150600.8.37.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | 0 | 6.4.0-150600.8.37.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP6 | kernel-syms-azure | 0 | 6.4.0-150600.8.37.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP7 | kernel-azure | 0 | 6.4.0-150700.20.3.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP7 | kernel-source-azure | 0 | 6.4.0-150700.20.3.1 |
| SUSE:Linux Enterprise Module for Public Cloud 15 SP7 | kernel-syms-azure | 0 | 6.4.0-150700.20.3.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | kernel-default | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | kernel-source | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Server 12 SP5-LTSS | kernel-syms | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-default | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-syms | 0 | 4.12.14-122.261.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| SUSE:Linux Enterprise Workstation Extension 15 SP7 | kernel-default | 0 | 6.4.0-150700.53.3.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt | 0 | 6.4.0-150600.10.39.1 |
| SUSE:Real Time Module 15 SP6 | kernel-rt_debug | 0 | 6.4.0-150600.10.39.1 |
| SUSE:Real Time Module 15 SP6 | kernel-source-rt | 0 | 6.4.0-150600.10.39.1 |
| SUSE:Real Time Module 15 SP6 | kernel-syms-rt | 0 | 6.4.0-150600.10.39.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-azure | 0 | 6.4.0-150600.8.37.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.50.1.150600.12.22.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-rt | 0 | 6.4.0-150600.10.39.1 |
| openSUSE:Leap 15.6 | kernel-rt_debug | 0 | 6.4.0-150600.10.39.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-source-azure | 0 | 6.4.0-150600.8.37.1 |
| openSUSE:Leap 15.6 | kernel-source-rt | 0 | 6.4.0-150600.10.39.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.50.1 |
| openSUSE:Leap 15.6 | kernel-syms-azure | 0 | 6.4.0-150600.8.37.1 |
| openSUSE:Leap 15.6 | kernel-syms-rt | 0 | 6.4.0-150600.10.39.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.50.1 |
Related vulnerabilities
- CVE-2025-39885 In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix recursive… Also affects linux
- CVE-2025-39883 In the Linux kernel, the following vulnerability has been resolved: mm/memory-failure… Also affects linux
- CVE-2025-39876 In the Linux kernel, the following vulnerability has been resolved: net: fec: Fix… Also affects linux
- CVE-2025-39869 In the Linux kernel, the following vulnerability has been resolved: dmaengine: ti: edma… Also affects linux
- CVE-2025-39873 In the Linux kernel, the following vulnerability has been resolved: can: xilinx_can… Also affects linux
- CVE-2025-39863 In the Linux kernel, the following vulnerability has been resolved: wifi: brcmfmac: fix… Also affects linux
- CVE-2025-39865 In the Linux kernel, the following vulnerability has been resolved: tee: fix NULL pointer… Also affects linux
- CVE-2025-39866 In the Linux kernel, the following vulnerability has been resolved: fs: writeback: fix… Also affects linux