CVE-2025-38193: Linux kernel · net_sched: sch_sfq: reject invalid perturb period
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1092.99~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1092.99~20.04.1, 5.15.0-1096.105~20.04.1, 5.15.0-1092.101~20.04.1 +63
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7856-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8052-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-7 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
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
References
- ubuntu.com/security/CVE-2025-38193 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38193 (opens in a new tab)
- git.kernel.org/linus/7ca52541c05c832d32b112274f81a985101f9ba8 (opens in a new tab)
- git.kernel.org/stable/c/0357da9149eac621f39e235a135ebf155f01f7c3 (opens in a new tab)
- git.kernel.org/stable/c/590b2d7d0beadba2aa576708a05a05f0aae39295 (opens in a new tab)
- git.kernel.org/stable/c/7ca52541c05c832d32b112274f81a985101f9ba8 (opens in a new tab)
- git.kernel.org/stable/c/956b5aebb349449b38d920d444ca1392d43719d1 (opens in a new tab)
- git.kernel.org/stable/c/b11a50544af691b787384089b68f740ae20a441b (opens in a new tab)
- git.kernel.org/stable/c/f9b97d466e6026ccbdda30bb5b71965b67ccbc82 (opens in a new tab)
- ubuntu.com/security/notices/USN-7856-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8028-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8031-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8052-1 (opens in a new tab)