In the Linux kernel, the following vulnerability has been resolved:

net/sched: Restrict conditions for adding duplicating netems to qdisc tree

netem_enqueue's duplication prevention logic breaks when a netem
resides in a qdisc tree with other netems - this can lead to a
soft lockup and OOM loop in netem_dequeue, as seen in [1].
Ensure that a duplicating netem cannot exist in a tree with other
netems.

Previous approaches suggested in discussions in chronological order:

1) Track duplication status or ttl in the sk_buff struct. Considered
too specific a use case to extend such a struct, though this would
be a resilient fix and address other previous and potential future
DOS bugs like the one described in loopy fun [2].

2) Restrict netem_enqueue recursion depth like in act_mirred with a
per cpu variable. However, netem_dequeue can call enqueue on its
child, and the depth restriction could be bypassed if the child is a
netem.

3) Use the same approach as in 2, but add metadata in netem_skb_cb
to handle the netem_dequeue case and track a packet's involvement
in duplication. This is an overly complex approach, and Jamal
notes that the skb cb can be overwritten to circumvent this
safeguard.

4) Prevent the addition of a netem to a qdisc tree if its ancestral
path contains a netem. However, filters and actions can cause a
packet to change paths when re-enqueued to the root from netem
duplication, leading us to the current solution: prevent a
duplicating netem from inhabiting the same tree as other netems.

[1] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/
[2] https://lwn.net/Articles/719297/

Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

NIST: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NIST: CWE-667

OR
          *cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

OR
          *cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.148
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.190
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5 up to (excluding) 5.10.241
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.16 up to (excluding) 6.16.1
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.15.10
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.42
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 2.6.13 up to (excluding) 5.4.297
          *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.102

CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html

CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html

kernel.org: https://git.kernel.org/stable/c/09317dfb681ac5a96fc69bea0c54441cf91b8270

kernel.org: https://git.kernel.org/stable/c/103c4e27ec9f5fe53022e46e976abf52c7221baf

kernel.org: https://git.kernel.org/stable/c/250f8796006c0f2bc638ce545f601d49ae8d528b

kernel.org: https://git.kernel.org/stable/c/325f5ec67cc0a77f2d0d453445b9857f1cd06c76

kernel.org: https://git.kernel.org/stable/c/795cb393e38977aa991e70a9363da0ee734b2114

kernel.org: https://git.kernel.org/stable/c/ad340a4b4adb855b18b3666f26ad65c8968e2deb

kernel.org: https://git.kernel.org/stable/c/cab2809944989889f88a1a8b5cff1c78460c72cb

kernel.org: https://git.kernel.org/stable/c/ec8e0e3d7adef940cdf9475e2352c0680189d14e

kernel.org: https://git.kernel.org/stable/c/f088b6ebe8797a3f948d2cae47f34bfb45cc6522

CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Types: Mailing List, Third Party Advisory

CVE: https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Types: Mailing List, Third Party Advisory

kernel.org: https://git.kernel.org/stable/c/09317dfb681ac5a96fc69bea0c54441cf91b8270 Types: Patch

kernel.org: https://git.kernel.org/stable/c/103c4e27ec9f5fe53022e46e976abf52c7221baf Types: Patch

kernel.org: https://git.kernel.org/stable/c/250f8796006c0f2bc638ce545f601d49ae8d528b Types: Patch

kernel.org: https://git.kernel.org/stable/c/325f5ec67cc0a77f2d0d453445b9857f1cd06c76 Types: Patch

kernel.org: https://git.kernel.org/stable/c/795cb393e38977aa991e70a9363da0ee734b2114 Types: Patch

kernel.org: https://git.kernel.org/stable/c/ad340a4b4adb855b18b3666f26ad65c8968e2deb Types: Patch

kernel.org: https://git.kernel.org/stable/c/cab2809944989889f88a1a8b5cff1c78460c72cb Types: Patch

kernel.org: https://git.kernel.org/stable/c/ec8e0e3d7adef940cdf9475e2352c0680189d14e Types: Patch

kernel.org: https://git.kernel.org/stable/c/f088b6ebe8797a3f948d2cae47f34bfb45cc6522 Types: Patch

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