CVE-2025-21703 Details
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.
A use-after-free vulnerability has been identified in the Linux kernel's netem module. The issue arises because the backlog of the child queuing discipline (qdisc) is not properly managed before notifying the parent qdisc. This oversight can cause the parent qdisc to miss important updates, particularly in the Deficit Round Robin (DRR) scheduling algorithm, which relies on these notifications to function correctly.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Feb 18, 2025References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| linux linux kernel | >= 5.4.288, < 5.4.291 >= 5.10.232, < 5.10.235 >= 5.15.175, < 5.15.179 >= 6.1.121, < 6.1.129 >= 6.6.67, < 6.6.78 >= 6.12.6, < 6.12.14 >= 6.13, < 6.13.3 6.14 rc1 |
CPE
Remediation
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Change History
9 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | kernel.org |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 23, 2026 | CVE Modified | kernel.org |
| Nov 3, 2025 | CVE Modified | CVE |
| Mar 24, 2025 | Initial Analysis | [email protected] |
| Mar 13, 2025 | CVE Modified | kernel.org |
| Feb 21, 2025 | CVE Modified | kernel.org |
| Feb 18, 2025 | CVE Modified | CISA-ADP |
| Feb 18, 2025 | New CVE Received | kernel.org |