Description
In the Linux kernel, the following vulnerability has been resolved: net_sched: ets: Fix double list add in class with netem as child qdisc As described in Gerrard's report [1], there are use cases where a netem child qdisc will make the parent qdisc's enqueue callback reentrant. In the case of ets, there won't be a UAF, but the code will add the same classifier to the list twice, which will cause memory corruption. In addition to checking for qlen being zero, this patch checks whether the class was already added to the active_list (cl_is_active) before doing the addition to cater for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/
Affected products
linux: linux kernel; debian: debian linux
References9
- git.kernel.org/stable/c/1a6d0c00fa07972384b0c308c72db091d49988b6 Patch
- git.kernel.org/stable/c/1f01e9f961605eb397c6ecd1d7b0233dfbf9077c Patch
- git.kernel.org/stable/c/24388ba0a1b1b6d4af1b205927ac7f7b119ee4ea Patch
- git.kernel.org/stable/c/554acc5a2ea9703e08023eb9a003f9e5a830a502 Patch
- git.kernel.org/stable/c/72c3da7e6ceb74e74ddbb5a305a35c9fdfcac6e3 Patch
- git.kernel.org/stable/c/9efb6a0fa88e0910d079fdfeb4f7ce4d4ac6c990 Patch
- git.kernel.org/stable/c/bc321f714de693aae06e3786f88df2975376d996 Patch
- lists.debian.org/debian-lts-announce/2025/08/msg00010.html Mailing List
- lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing List
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 14 · as of 7 November 2026
- CWE
- CWE-415
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.