IT

Tracker / CVE-2025-39766

CVE-2025-39766

High 7.8

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.

Affected products and versions

debian debian_linux
linux linux_kernel
linux linux_kernel · 4.19 → 5.4.297
linux linux_kernel · 5.11 → 5.15.190
linux linux_kernel · 5.16 → 6.1.149
linux linux_kernel · 5.5 → 5.10.241
linux linux_kernel · 6.13 → 6.16.4
linux linux_kernel · 6.2 → 6.6.103
linux linux_kernel · 6.7 → 6.12.44

Analysis

This page is not indexable yet.Until it carries original analysis — what it actually exposes, how to check in two minutes whether a system was touched, what to do if it was — the page stays noindex. The database decides that, not the template.

References