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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2025-39766 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit The following setup can trigger a WARNING in htb_activate due to the condition: !cl->leaf.q->q.qlen tc qdisc del dev lo root tc qdisc add dev lo root handle 1: htb default 1 tc class add dev lo parent 1: classid 1:1 \ htb rate 64bit tc qdisc add dev lo parent 1:1 handle f: \ cake memlimit 1b ping -I lo -f -c1 -s64 -W0.001 127.0.0.1 This is because the low memlimit leads to a low buffer_limit, which causes packet dropping. However, cake_enqueue still returns NET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an empty child qdisc. We should return NET_XMIT_CN when packets are dropped from the same tin and flow. I do not believe return value of NET_XMIT_CN is necessary for packet drops in the case of ack filtering, as that is meant to optimize performance, not to signal congestion.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/0dacfc5372e314d1219f03e64dde3ab495a5a25e kernel.org Patch 
https://git.kernel.org/stable/c/15de71d06a400f7fdc15bf377a2552b0ec437cf5 kernel.org Patch 
https://git.kernel.org/stable/c/62d591dde4defb1333d202410609c4ddeae060b3 kernel.org Patch 
https://git.kernel.org/stable/c/710866fc0a64eafcb8bacd91bcb1329eb7e5035f kernel.org Patch 
https://git.kernel.org/stable/c/7689ab22de36f8db19095f6bdf11f28cfde92f5c kernel.org Patch 
https://git.kernel.org/stable/c/aa12ee1c1bd260943fd6ab556d8635811c332eeb kernel.org Patch 
https://git.kernel.org/stable/c/de04ddd2980b48caa8d7e24a7db2742917a8b280 kernel.org Patch 
https://git.kernel.org/stable/c/ff57186b2cc39766672c4c0332323933e5faaa88 kernel.org Patch 
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html CVE Mailing List  Third Party Advisory 
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html CVE Mailing List  Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
NVD-CWE-noinfo Insufficient Information cwe source acceptance level NIST  

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Change History

3 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-39766
NVD Published Date:
09/11/2025
NVD Last Modified:
01/09/2026
Source:
kernel.org