Vulnerability Database

373,546

Total vulnerabilities in the database

CVE-2025-38327 — linux / linux_kernel

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

fgraph: Do not enable function_graph tracer when setting funcgraph-args

When setting the funcgraph-args option when function graph tracer is net enabled, it incorrectly enables it. Worse, it unregisters itself when it was never registered. Then when it gets enabled again, it will register itself a second time causing a WARNing.

~# echo 1 > /sys/kernel/tracing/options/funcgraph-args ~# head -20 /sys/kernel/tracing/trace

tracer: nop

entries-in-buffer/entries-written: 813/26317372 #P:8

_-----=> irqs-off/BH-disabled

/ _----=> need-resched

| / _---=> hardirq/softirq

|| / _--=> preempt-depth

||| / _-=> migrate-disable

|||| / delay

TASK-PID CPU# ||||| TIMESTAMP FUNCTION

| | | ||||| | |

<idle>-0 [007] d..4. 358.966010: 7) 1.692 us | fetch_next_timer_interrupt(basej=4294981640, basem=357956000000, base_local=0xffff88823c3ae040, base_global=0xffff88823c3af300, tevt=0xffff888100e47cb8); <idle>-0 [007] d..4. 358.966012: 7) | tmigr_cpu_deactivate(nextexp=357988000000) { <idle>-0 [007] d..4. 358.966013: 7) | _raw_spin_lock(lock=0xffff88823c3b2320) { <idle>-0 [007] d..4. 358.966014: 7) 0.981 us | preempt_count_add(val=1); <idle>-0 [007] d..5. 358.966017: 7) 1.058 us | do_raw_spin_lock(lock=0xffff88823c3b2320); <idle>-0 [007] d..4. 358.966019: 7) 5.824 us | } <idle>-0 [007] d..5. 358.966021: 7) | tmigr_inactive_up(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) { <idle>-0 [007] d..5. 358.966022: 7) | tmigr_update_events(group=0xffff888100cb9000, child=0x0, data=0xffff888100e47bc0) {

Notice the "tracer: nop" at the top there. The current tracer is the "nop" tracer, but the content is obviously the function graph tracer.

Enabling function graph tracing will cause it to register again and trigger a warning in the accounting:

~# echo function_graph > /sys/kernel/tracing/current_tracer -bash: echo: write error: Device or resource busy

With the dmesg of:

------------[ cut here ]------------ WARNING: CPU: 7 PID: 1095 at kernel/trace/ftrace.c:3509 ftrace_startup_subops+0xc1e/0x1000 Modules linked in: kvm_intel kvm irqbypass CPU: 7 UID: 0 PID: 1095 Comm: bash Not tainted 6.16.0-rc2-test-00006-gea03de4105d3 #24 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:ftrace_startup_subops+0xc1e/0x1000 Code: 48 b8 22 01 00 00 00 00 ad de 49 89 84 24 88 01 00 00 8b 44 24 08 89 04 24 e9 c3 f7 ff ff c7 04 24 ed ff ff ff e9 b7 f7 ff ff <0f> 0b c7 04 24 f0 ff ff ff e9 a9 f7 ff ff c7 04 24 f4 ff ff ff e9 RSP: 0018:ffff888133cff948 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 1ffff1102679ff31 RCX: 0000000000000000 RDX: 1ffffffff0b27a60 RSI: ffffffff8593d2f0 RDI: ffffffff85941140 RBP: 00000000000c2041 R08: ffffffffffffffff R09: ffffed1020240221 R10: ffff88810120110f R11: ffffed1020240214 R12: ffffffff8593d2f0 R13: ffffffff8593d300 R14: ffffffff85941140 R15: ffffffff85631100 FS: 00007f7ec6f28740(0000) GS:ffff8882b5251000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7ec6f181c0 CR3: 000000012f1d0005 CR4: 0000000000172ef0 Call Trace: <TASK> ? __pfx_ftrace_startup_subops+0x10/0x10 ? find_held_lock+0x2b/0x80 ? ftrace_stub_direct_tramp+0x10/0x10 ? ftrace_stub_direct_tramp+0x10/0x10 ? trace_preempt_on+0xd0/0x110 ? __pfx_trace_graph_entry_args+0x10/ ---truncated---

  • Published: Jul 10, 2025
  • Updated: Nov 19, 2025
  • CVE: CVE-2025-38327
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Medium
  • Score: 5.5
  • AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

No CWE or OWASP classifications available.

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.