# CVE-2025-21733: tracing/osnoise: Fix resetting of tracepoints > A logic error in the Linux kernel's osnoise tracer causes tracepoint registration warnings and potential instability when toggling workload options. - **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:** 27 Feb 2025 - **Updated:** 11 May 2026 - **Also known as:** BELL-CVE-2025-21733, DEBIAN-CVE-2025-21733, GHSA-xrhp-qwwp-fpx8, ROOT-OS-UBUNTU-2404-CVE-2025-21733, UBUNTU-CVE-2025-21733 ## What is CVE-2025-21733? CVE-2025-21733 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 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: tracing/osnoise: Fix resetting of tracepoints If a timerlat tracer is started with the osnoise option OSNOISE_WORKLOAD disabled, but then that option is enabled and timerlat is removed, the tracepoints that were enabled on timerlat registration do not get disabled. If the option is disabled again and timelat is started, then it triggers a warning in the tracepoint code due to registering the tracepoint again without ever disabling it. Do not use the same user space defined options to know to disable the tracepoints when timerlat is removed. Instead, set a global flag when it is enabled and use that flag to know to disable the events. ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo timerlat > /sys/kernel/tracing/current_tracer ~# echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo nop > /sys/kernel/tracing/current_tracer ~# echo NO_OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options ~# echo timerlat > /sys/kernel/tracing/current_tracer Triggers: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 1337 at kernel/tracepoint.c:294 tracepoint_add_func+0x3b6/0x3f0 Modules linked in: CPU: 6 UID: 0 PID: 1337 Comm: rtla Not tainted 6.13.0-rc4-test-00018-ga867c441128e-dirty #73 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:tracepoint_add_func+0x3b6/0x3f0 Code: 48 8b 53 28 48 8b 73 20 4c 89 04 24 e8 23 59 11 00 4c 8b 04 24 e9 36 fe ff ff 0f 0b b8 ea ff ff ff 45 84 e4 0f 84 68 fe ff ff <0f> 0b e9 61 fe ff ff 48 8b 7b 18 48 85 ff 0f 84 4f ff ff ff 49 8b RSP: 0018:ffffb9b003a87ca0 EFLAGS: 00010202 RAX: 00000000ffffffef RBX: ffffffff92f30860 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff9bf59e91ccd0 RDI: ffffffff913b6410 RBP: 000000000000000a R08: 00000000000005c7 R09: 0000000000000002 R10: ffffb9b003a87ce0 R11: 0000000000000002 R12: 0000000000000001 R13: ffffb9b003a87ce0 R14: ffffffffffffffef R15: 0000000000000008 FS: 00007fce81209240(0000) GS:ffff9bf6fdd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055e99b728000 CR3: 00000001277c0002 CR4: 0000000000172ef0 Call Trace: ? __warn.cold+0xb7/0x14d ? tracepoint_add_func+0x3b6/0x3f0 ? report_bug+0xea/0x170 ? handle_bug+0x58/0x90 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? __pfx_trace_sched_migrate_callback+0x10/0x10 ? tracepoint_add_func+0x3b6/0x3f0 ? __pfx_trace_sched_migrate_callback+0x10/0x10 ? __pfx_trace_sched_migrate_callback+0x10/0x10 tracepoint_probe_register+0x78/0xb0 ? __pfx_trace_sched_migrate_callback+0x10/0x10 osnoise_workload_start+0x2b5/0x370 timerlat_tracer_init+0x76/0x1b0 tracing_set_tracer+0x244/0x400 tracing_set_trace_write+0xa0/0xe0 vfs_write+0xfc/0x570 ? do_sys_openat2+0x9c/0xe0 ksys_write+0x72/0xf0 do_syscall_64+0x79/0x1c0 entry_SYSCALL_64_after_hwframe+0x76/0x7e ## Which versions are affected by CVE-2025-21733? It affects 1 product. Products: Linux kernel. ## How do I fix CVE-2025-21733? Apply the vendor's patch. ## Is CVE-2025-21733 being exploited? There is no known exploitation of CVE-2025-21733 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-2025-21733 and fix it if it is affected. What it is: CVE-2025-21733 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 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-2025-21733 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-2025-21733/ (Markdown: https://insights.sbomify.com/CVE-2025-21733/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2025-21733 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-21733 - OSV: https://osv.dev/vulnerability/CVE-2025-21733 --- From sbomify Insights: https://insights.sbomify.com/CVE-2025-21733/ Summaries are generated and may contain mistakes; the official description above is the record.