CVE-2026-74284: Linux kernel · net/sched: sch_hfsc: Don't make class passive twice
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +41
Exploitation evidence
Disclosed: evidence found.
CVE published 15 Aug 2026
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.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available that fixes this issue by modifying the update_vf() function to only mark a class as passive if it is currently active, preventing double passive transitions. Users should apply the official Linux kernel updates that include this fix. The vendor advisory confirms that this vulnerability has been resolved.
Description
A vulnerability in the Linux kernel's net/sched subsystem (sch_hfsc) could cause the queuing discipline (qdisc) to stall due to improper handling of class passive state transitions during packet dequeue operations. This flaw leads to a parent class being incorrectly marked as inactive, preventing further dequeuing of packets from active sibling classes. The issue has been fixed by ensuring that the class is only marked passive once per dequeue cycle.
References
- nvd.nist.gov/vuln/detail/CVE-2026-74284 (opens in a new tab)
- git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7 (opens in a new tab)
- git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10 (opens in a new tab)
- git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0 (opens in a new tab)
- git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8 (opens in a new tab)
- git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc (opens in a new tab)
- git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e (opens in a new tab)
- git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227 (opens in a new tab)
- git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b (opens in a new tab)
- ubuntu.com/security/CVE-2026-74284 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74284 (opens in a new tab)
- git.kernel.org/linus/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8 (opens in a new tab)
- ubuntu.com/security/notices/USN-8876-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8889-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8887-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8888-2 (opens in a new tab)