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CVE-2025-37890 is a use-after-free vulnerability in the Linux kernel's Hierarchical Fair Service Curve (HFSC) network scheduler when an HFSC class has a netem child queueing discipline. HFSC incorrectly assumes that a zero child queue length proves the class has not already been inserted into its virtual-time or eligible-time scheduling trees. Netem packet duplication can invalidate this assumption, allowing reentrant processing to insert the class twice and cause a use-after-free condition. The flaw can cause a kernel crash and potentially enable privilege escalation. The fix checks the n_active class variable to prevent duplicate tree insertion.
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A use-after-free vulnerability in the Linux kernel's HFSC network scheduler when a class has a netem child queueing discipline. Incorrect assumptions about queue length can cause duplicate insertion into scheduling trees. The reference assigns a CVSS v3 base score of 7.8, with local attack access, low privileges required, and high confidentiality, integrity, and availability impact.
A use-after-free vulnerability in the Linux kernel's HFSC network scheduler when a class has a netem child queueing discipline. Incorrect assumptions about queue length can cause duplicate insertion into scheduling trees during reentrant processing. The fix checks the n_active class variable to prevent duplicate insertion. The reference assigns a CVSS v3 base score of 7.8, with local access and low privileges required.
A use-after-free vulnerability in the Linux kernel HFSC network scheduler when a class has netem configured as a child queuing discipline.
A use-after-free vulnerability in a Linux kernel HFSC traffic-scheduling class with netem as its child queueing discipline. Red Hat addresses it in Important-rated advisory RHSA-2025:12662. The kernel update requires a reboot.
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Cross-references every affected SKU, including bundled OEM variants.
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