PT-2025-8997 · Linux+9 · Linux Kernel+9
Liu Jian
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Published
2025-01-18
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Updated
2026-04-20
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CVE-2025-21806
CVSS v3.1
5.5
Medium
| Vector | AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Name of the Vulnerable Software and Affected Versions
Linux kernel versions prior to 6.13.0-rc7+
Description
A problem was encountered during stability testing in the Linux kernel, where the NAPI poll function
process backlog() returned 1, exceeding its budget of 0, when net.core.dev weight was set to 0. This caused a double add issue in the list, resulting in a warning. The issue occurs when the napi's weight is set to 0, allowing process backlog() to return 0 and clear the NAPI STATE SCHED bit of napi->state, causing the napi to be re-polled until do softirq() times out. Making the napi's weight always non-zero solves this problem. Triggering this issue requires system-wide admin privileges.Recommendations
For Linux kernel versions prior to 6.13.0-rc7+, as a temporary workaround, consider setting
net.core.dev weight to a non-zero value to prevent the issue.
To resolve the issue, update the Linux kernel to a version where this problem has been fixed, ensuring that net.core.dev weight is always non-zero.Exploit
Fix
RCE
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Weakness Enumeration
Related Identifiers
Affected Products
Almalinux
Astra Linux
Debian
Linuxmint
Linux Kernel
Red Hat
Red Os
Rocky Linux
Suse
Ubuntu