Linux KernelOperating system · Linux
CVE-2025-38493
A fix is available.
Upgrade to 6.6.100 / 6.12.40 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click
Patch available
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: tracing/osnoise: Fix crash in timerlat_dump_stack() We have observed kernel panics when using timerlat with stack saving, with the following dmesg output: memcpy: detected buffer overflow: 88 byte write of buffer size 0 WARNING: CPU: 2 PID: 8153 at lib/string_helpers.c:1032 __fortify_report+0x55/0xa0 CPU: 2 UID: 0 PID: 8153 Comm: timerlatu/2 Kdump: loaded Not tainted 6.15.3-200.fc42.x86_64 #1 PREEMPT(lazy) Call Trace: <TASK> ? trace_buffer_lock_reserve+0x2a/0x60 __fortify_panic+0xd/0xf __timerlat_dump_stack.cold+0xd/0xd timerlat_dump_stack.part.0+0x47/0x80 timerlat_fd_read+0x36d/0x390 vfs_read+0xe2/0x390 ? syscall_exit_to_user_mode+0x1d5/0x210 ksys_read+0x73/0xe0 do_syscall_64+0x7b/0x160 ? exc_page_fault+0x7e/0x1a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e __timerlat_dump_stack() constructs the ftrace stack entry like this: struct stack_entry *entry; ... memcpy(&entry->caller, fstack->calls, size); entry->size = fstack->nr_entries; Since commit e7186af7fb26 ("tracing: Add back FORTIFY_SOURCE logic to kernel_stack event structure"), struct stack_entry marks its caller field with __counted_by(size). At the time of the memcpy, entry->size contains garbage from the ringbuffer, which under some circumstances is zero, triggering a kernel panic by buffer overflow. Populate the size field before the memcpy so that the out-of-bounds check knows the correct size. This is analogous to __ftrace_trace_stack().
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisA detailed technical summary for this CVE is being prepared.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
Affected:
>= 6.6, < 6.6.100>= 6.7, < 6.12.40>= 6.13, < 6.15.8= 6.16CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped
Upgrade available
Upgrade to 6.6.100 / 6.12.40 / 6.15.8 or later
Fixed in
6.6.1006.12.406.15.8
Vendor patch
git.kernel.org →
Recommended fix
High confidence
Linux Kernel >= 6.6.100, >= 6.12.40, >= 6.15.8, or >= 6.17 (depending on which major version branch you are on)
- Upgrade the Linux kernel to a version that includes the fix: For 6.6.x kernels, upgrade to >= 6.6.100; for 6.7.x through 6.12.x kernels, upgrade to >= 6.12.40; for 6.13.x through 6.15.x kernels, upgrade to >= 6.15.8; for 6.16.x, upgrade to 6.17 or later
- After kernel upgrade, verify the fix is present by checking that the commit 7bb9ea515cda027c9e717e27fefcf34f092e7c41 is included in the kernel version
- Reboot into the new kernel to apply the fix
- If running osnoise/timerlat tracer with stack saving enabled, verify normal operation without the buffer overflow panic
Caveat Kernel upgrades may require system reboot and could have compatibility implications with custom kernel modules or specific hardware drivers; ensure to test in a staging environment first
Generated from the published advisory — verify against the referenced sources before acting.
We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600.
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Free · runs locally
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-38493 in production — separate from our analysis above.
Know something about CVE-2025-38493?
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
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