# CVE-2025-39831: fbnic: Move phylink resume out of service_task and into open/close > A locking assertion failure in the fbnic network driver during power management resume can cause a kernel warning or potential denial of service. - **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 16 Sep 2025 - **Updated:** 11 May 2026 - **Also known as:** BELL-CVE-2025-39831, DEBIAN-CVE-2025-39831, GHSA-7j9w-q7j7-gqpq, ROOT-OS-DEBIAN-13-CVE-2025-39831, UBUNTU-CVE-2025-39831 ## What is CVE-2025-39831? CVE-2025-39831 is a medium-severity vulnerability in Linux kernel, published on 16 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description In the Linux kernel, the following vulnerability has been resolved: fbnic: Move phylink resume out of service_task and into open/close The fbnic driver was presenting with the following locking assert coming out of a PM resume: [ 42.208116][ T164] RTNL: assertion failed at drivers/net/phy/phylink.c (2611) [ 42.208492][ T164] WARNING: CPU: 1 PID: 164 at drivers/net/phy/phylink.c:2611 phylink_resume+0x190/0x1e0 [ 42.208872][ T164] Modules linked in: [ 42.209140][ T164] CPU: 1 UID: 0 PID: 164 Comm: bash Not tainted 6.17.0-rc2-virtme #134 PREEMPT(full) [ 42.209496][ T164] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-5.fc42 04/01/2014 [ 42.209861][ T164] RIP: 0010:phylink_resume+0x190/0x1e0 [ 42.210057][ T164] Code: 83 e5 01 0f 85 b0 fe ff ff c6 05 1c cd 3e 02 01 90 ba 33 0a 00 00 48 c7 c6 20 3a 1d a5 48 c7 c7 e0 3e 1d a5 e8 21 b8 90 fe 90 <0f> 0b 90 90 e9 86 fe ff ff e8 42 ea 1f ff e9 e2 fe ff ff 48 89 ef [ 42.210708][ T164] RSP: 0018:ffffc90000affbd8 EFLAGS: 00010296 [ 42.210983][ T164] RAX: 0000000000000000 RBX: ffff8880078d8400 RCX: 0000000000000000 [ 42.211235][ T164] RDX: 0000000000000000 RSI: 1ffffffff4f10938 RDI: 0000000000000001 [ 42.211466][ T164] RBP: 0000000000000000 R08: ffffffffa2ae79ea R09: fffffbfff4b3eb84 [ 42.211707][ T164] R10: 0000000000000003 R11: 0000000000000000 R12: ffff888007ad8000 [ 42.211997][ T164] R13: 0000000000000002 R14: ffff888006a18800 R15: ffffffffa34c59e0 [ 42.212234][ T164] FS: 00007f0dc8e39740(0000) GS:ffff88808f51f000(0000) knlGS:0000000000000000 [ 42.212505][ T164] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 42.212704][ T164] CR2: 00007f0dc8e9fe10 CR3: 000000000b56d003 CR4: 0000000000772ef0 [ 42.213227][ T164] PKRU: 55555554 [ 42.213366][ T164] Call Trace: [ 42.213483][ T164] [ 42.213565][ T164] __fbnic_pm_attach.isra.0+0x8e/0xa0 [ 42.213725][ T164] pci_reset_function+0x116/0x1d0 [ 42.213895][ T164] reset_store+0xa0/0x100 [ 42.214025][ T164] ? pci_dev_reset_attr_is_visible+0x50/0x50 [ 42.214221][ T164] ? sysfs_file_kobj+0xc1/0x1e0 [ 42.214374][ T164] ? sysfs_kf_write+0x65/0x160 [ 42.214526][ T164] kernfs_fop_write_iter+0x2f8/0x4c0 [ 42.214677][ T164] ? kernfs_vma_page_mkwrite+0x1f0/0x1f0 [ 42.214836][ T164] new_sync_write+0x308/0x6f0 [ 42.214987][ T164] ? __lock_acquire+0x34c/0x740 [ 42.215135][ T164] ? new_sync_read+0x6f0/0x6f0 [ 42.215288][ T164] ? lock_acquire.part.0+0xbc/0x260 [ 42.215440][ T164] ? ksys_write+0xff/0x200 [ 42.215590][ T164] ? perf_trace_sched_switch+0x6d0/0x6d0 [ 42.215742][ T164] vfs_write+0x65e/0xbb0 [ 42.215876][ T164] ksys_write+0xff/0x200 [ 42.215994][ T164] ? __ia32_sys_read+0xc0/0xc0 [ 42.216141][ T164] ? do_user_addr_fault+0x269/0x9f0 [ 42.216292][ T164] ? rcu_is_watching+0x15/0xd0 [ 42.216442][ T164] do_syscall_64+0xbb/0x360 [ 42.216591][ T164] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 42.216784][ T164] RIP: 0033:0x7f0dc8ea9986 A bit of digging showed that we were invoking the phylink_resume as a part of the fbnic_up path when we were enabling the service task while not holding the RTNL lock. We should be enabling this sooner as a part of the ndo_open path and then just letting the service task come online later. This will help to enforce the correct locking and brings the phylink interface online at the same time as the network interface, instead of at a later time. I tested this on QEMU to verify this was working by putting the system to sleep using "echo mem > /sys/power/state" to put the system to sleep in the guest and then using the command "system_wakeup" in the QEMU monitor. ## Which versions are affected by CVE-2025-39831? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2025-39831? Apply the vendor's patch. ## Is CVE-2025-39831 being exploited? There is no known exploitation of CVE-2025-39831 in the wild and no public exploit code. ## Other vulnerabilities in Linux kernel - [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild) - [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild) - [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild) - [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild) - [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2025-39831 and fix it if it is affected. What it is: CVE-2025-39831 is a medium-severity vulnerability in Linux kernel, published on 16 Sep 2025. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2025-39831 in the wild and no public exploit code. Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2025-39831/ (Markdown: https://insights.sbomify.com/CVE-2025-39831/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-39831 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-39831 - OSV: https://osv.dev/vulnerability/CVE-2025-39831 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-39831/ Summaries are generated and may contain mistakes; the official description above is the record.