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Linux KernelOperating system · Linux

CVE-2025-38193

MEDIUM · 5.5 CVSS v3.1 Published 2025-07-04
Fix available
A fix is available. Upgrade to 5.4.297 / 5.10.240 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 · unedited
In the Linux kernel, the following vulnerability has been resolved: net_sched: sch_sfq: reject invalid perturb period Gerrard Tai reported that SFQ perturb_period has no range check yet, and this can be used to trigger a race condition fixed in a separate patch. We want to make sure ctl->perturb_period * HZ will not overflow and is positive. tc qd add dev lo root sfq perturb -10 # negative value : error Error: sch_sfq: invalid perturb period. tc qd add dev lo root sfq perturb 1000000000 # too big : error Error: sch_sfq: invalid perturb period. tc qd add dev lo root sfq perturb 2000000 # acceptable value tc -s -d qd sh dev lo qdisc sfq 8005: root refcnt 2 limit 127p quantum 64Kb depth 127 flows 128 divisor 1024 perturb 2000000sec Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0) backlog 0b 0p requeues 0

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 analysis
How this class of weakness works · CWE-190

An arithmetic operation produces a value too large for its type and wraps around to an unexpected — often tiny or negative — number. That miscalculated value then drives a memory allocation or a bounds check, opening the door to corruption. The fix is checked arithmetic and validating sizes before they're used.

General guidance for the integer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:>= 2.6.13, < 5.4.297>= 5.5, < 5.10.240>= 5.11, < 5.15.186>= 5.16, < 6.1.142>= 6.2, < 6.6.95>= 6.7, < 6.12.35>= 6.13, < 6.15.4= 2.6.12= 6.16
Debian LinuxOperating system
Affected:= 11.0

CVSS 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 5.4.297 / 5.10.240 / 5.15.186 or later
Fixed in 5.4.2975.10.2405.15.186
Vendor patch git.kernel.org →
Recommended fix High confidence

Upgrade Linux kernel to 5.4.297+, 5.10.240+, 5.15.186+, or 6.1.142+ (or latest stable kernel in your branch); Debian 11 users should apply available security updates

  1. Identify the currently running kernel version using `uname -r`
  2. Determine which version range your current kernel falls into from the affected versions list
  3. Upgrade to a kernel version that includes the fix: for 5.4.x branch upgrade to >= 5.4.297, for 5.10.x upgrade to >= 5.10.240, for 5.15.x upgrade to >= 5.15.186, or for 6.1.x upgrade to >= 6.1.142
  4. On Debian 11 (Bullseye), apply vendor security updates: `apt update && apt upgrade linux-image-*` to receive the patched kernel
  5. Reboot the system to load the fixed kernel
  6. Verify the fix is applied by checking kernel version with `uname -r` and testing SFQ configuration with valid perturb period values
Caveat Kernel upgrades may require system reboot and could introduce compatibility changes with third-party kernel modules or custom drivers

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 $2,850. Get the upgrade done

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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 sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-38193 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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