Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As… (CVE-2025-37890)
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
AI Analysis
Technical Summary
The Red Hat security advisory RHSA-2025:16538 provides a live patch module update for Red Hat Enterprise Linux 9 kernel version 5.14.0-570.17.1.el9_6. It addresses five vulnerabilities: CVE-2025-37890 (a use-after-free in net_sched hfsc class with netem child qdisc), CVE-2025-38001 (reentrant enqueue causing duplicate class addition to eltree), CVE-2025-38000 (queue length accounting bug in hfsc_enqueue), CVE-2025-38350 (missing notifications when child class becomes empty), and CVE-2025-38380 (initialization issue in i2c/designware). The patch is distributed as a kpatch live patch module and requires rebooting the system to apply changes. Red Hat classifies the update as important, indicating a high severity level for the vulnerabilities fixed. The advisory references multiple bugzilla entries and CVE pages for further details. No explicit CVSS scores are provided.
Potential Impact
The vulnerabilities fixed include a use-after-free condition which can lead to memory corruption, potential instability or privilege escalation in the kernel's network scheduling subsystem. Other flaws involve incorrect handling of enqueue operations and queue length accounting, which may affect network traffic control reliability and correctness. The initialization issue in the i2c/designware driver could cause improper hardware initialization. Collectively, these issues pose a high security risk to affected Red Hat Enterprise Linux 9 systems running the specified kernel version, potentially impacting system stability and security.
Mitigation Recommendations
An official patch is available as the kpatch-patch-5_14_0-570_17_1 live patch module for Red Hat Enterprise Linux 9 kernel 5.14.0-570.17.1.el9_6. Users should apply this update promptly following Red Hat's guidance at https://access.redhat.com/articles/11258. A system reboot is required for the update to take effect. No additional mitigation steps are indicated by the vendor advisory.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As… (CVE-2025-37890)
Description
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
CVSS v3.1
Score 7.8high
Affected software
pkg:rpm/redhat/kernel-livepatchRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Red Hat security advisory RHSA-2025:16538 provides a live patch module update for Red Hat Enterprise Linux 9 kernel version 5.14.0-570.17.1.el9_6. It addresses five vulnerabilities: CVE-2025-37890 (a use-after-free in net_sched hfsc class with netem child qdisc), CVE-2025-38001 (reentrant enqueue causing duplicate class addition to eltree), CVE-2025-38000 (queue length accounting bug in hfsc_enqueue), CVE-2025-38350 (missing notifications when child class becomes empty), and CVE-2025-38380 (initialization issue in i2c/designware). The patch is distributed as a kpatch live patch module and requires rebooting the system to apply changes. Red Hat classifies the update as important, indicating a high severity level for the vulnerabilities fixed. The advisory references multiple bugzilla entries and CVE pages for further details. No explicit CVSS scores are provided.
Potential Impact
The vulnerabilities fixed include a use-after-free condition which can lead to memory corruption, potential instability or privilege escalation in the kernel's network scheduling subsystem. Other flaws involve incorrect handling of enqueue operations and queue length accounting, which may affect network traffic control reliability and correctness. The initialization issue in the i2c/designware driver could cause improper hardware initialization. Collectively, these issues pose a high security risk to affected Red Hat Enterprise Linux 9 systems running the specified kernel version, potentially impacting system stability and security.
Mitigation Recommendations
An official patch is available as the kpatch-patch-5_14_0-570_17_1 live patch module for Red Hat Enterprise Linux 9 kernel 5.14.0-570.17.1.el9_6. Users should apply this update promptly following Red Hat's guidance at https://access.redhat.com/articles/11258. A system reboot is required for the update to take effect. No additional mitigation steps are indicated by the vendor advisory.
Technical Details
- Gcve Source
- db.gcve.eu
- Csaf Category
- csaf_security_advisory
- Csaf Version
- 2.0
- Publisher
- Red Hat Product Security
- Advisory Id
- RHSA-2025:16538
- Cve Count
- 5
- Additional Cves
- ["CVE-2025-38000","CVE-2025-38001","CVE-2025-38350","CVE-2025-38380"]
Threat ID: 6a3caf114853345fc153d15e
Added to database: 06/25/2026, 04:31:13 UTC
Last enriched: 06/25/2026, 04:47:48 UTC
Last updated: 09/10/2026, 19:24:56 UTC
Views: 71
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