In the Linux kernel, the following vulnerability has been resolved:

netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()

qdisc_tree_reduce_backlog() notifies parent qdisc only if child
qdisc becomes empty, therefore we need to reduce the backlog of the
child qdisc before calling it. Otherwise it would miss the opportunity
to call cops->qlen_notify(), in the case of DRR, it resulted in UAF
since DRR uses ->qlen_notify() to maintain its active list.
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4102-1 linux-6.1 security update
EUVD EUVD EUVD-2025-4525 In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
Ubuntu USN Ubuntu USN USN-7445-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7448-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7455-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7455-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7455-3 Linux kernel (Real-time) vulnerabilities
Ubuntu USN Ubuntu USN USN-7455-4 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-7455-5 Linux kernel (AWS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7459-1 Linux kernel (Intel IoTG) vulnerabilities
Ubuntu USN Ubuntu USN USN-7459-2 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7460-1 Linux kernel (Azure FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7461-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7461-2 Linux kernel (FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7461-3 Linux kernel (Xilinx ZynqMP) vulnerabilities
Ubuntu USN Ubuntu USN USN-7462-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7462-2 Linux kernel (AWS FIPS) vulnerabilities
Ubuntu USN Ubuntu USN USN-7475-1 Linux kernel (Xilinx ZynqMP) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 03 Nov 2025 20:30:00 +0000

Type Values Removed Values Added
References

Mon, 24 Mar 2025 18:00:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel

Thu, 13 Mar 2025 12:30:00 +0000


Fri, 21 Feb 2025 14:00:00 +0000


Thu, 20 Feb 2025 02:45:00 +0000

Type Values Removed Values Added
Metrics threat_severity

Important

threat_severity

Moderate


Wed, 19 Feb 2025 14:00:00 +0000


Tue, 18 Feb 2025 16:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Tue, 18 Feb 2025 14:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() notifies parent qdisc only if child qdisc becomes empty, therefore we need to reduce the backlog of the child qdisc before calling it. Otherwise it would miss the opportunity to call cops->qlen_notify(), in the case of DRR, it resulted in UAF since DRR uses ->qlen_notify() to maintain its active list.
Title netem: Update sch->q.qlen before qdisc_tree_reduce_backlog()
References

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-11-03T19:35:52.049Z

Reserved: 2024-12-29T08:45:45.751Z

Link: CVE-2025-21703

cve-icon Vulnrichment

Updated: 2025-02-18T15:38:38.582Z

cve-icon NVD

Status : Modified

Published: 2025-02-18T15:15:18.633

Modified: 2025-11-03T20:17:10.003

Link: CVE-2025-21703

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-02-18T00:00:00Z

Links: CVE-2025-21703 - Bugzilla

cve-icon OpenCVE Enrichment

No data.