CVE-2025-38001
What it is
In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Address reentrant enqueue adding class to eltree twice Savino says: "We are writing to report that this recent patch (141d34391abbb315d68556b7c67ad97885407547) [1] can be bypassed, and a UAF can still occur when HFSC is utilized with NETEM. The patch only checks the cl->cl_nactive field to determine whether it is the first insertion or not [2], but this field is only incremented by init_vf [3]. By using HFSC_RSC (which uses init_ed) [4], it is possible to bypass the check and insert the class twice in the eltree. Under normal conditions, this would lead to an infinite loop in hfsc_dequeue for the reasons we already explained in this report [5]. However, if TBF is added as root qdisc and it is configured with a very low rate, it can be utilized to prevent packets from being dequeued. This behavior can be exploited to perform subsequent insertions in the HFSC eltree and cause a UAF." To fix both the UAF and the infinite loop, with netem as an hfsc child, check explicitly in hfsc_enqueue whether the class is already in the eltree whenever the HFSC_RSC flag is set. [1] https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=141d34391abbb315d68556b7c67ad97885407547 [2] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L1572 [3] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L677 [4] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L1574 [5] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/T/#u
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.6% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.6% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.6% · EPSS, next 30 days
- Weakness
- CWE-835
- Record status
- Modified
Affected
- Linux Kernel < 5.4.294
- Linux Kernel < 5.10.238
- Linux Kernel < 5.15.185
- Linux Kernel < 6.1.141
- Linux Kernel < 6.6.93
- Linux Kernel < 6.12.32
- Linux Kernel < 6.14.10
- Linux Kernel < 6.15.1
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-38001.md and follow it. Check whether this project is affected by CVE-2025-38001. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/295f7c579b07b5b7cf2dffe485f71cc2f27647cb
- https://git.kernel.org/stable/c/2c928b3a0b04a431ffcd6c8b7d88a267124a3a28
- https://git.kernel.org/stable/c/2f2190ce4ca972051cac6a8d7937448f8cb9673c
- https://git.kernel.org/stable/c/39ed887b1dd2d6b720f87e86692ac3006cc111c8
- https://git.kernel.org/stable/c/4e38eaaabfb7fffbb371a51150203e19eee5d70e
- https://git.kernel.org/stable/c/6672e6c00810056acaac019fe26cdc26fee8a66c
- https://git.kernel.org/stable/c/a0ec22fa20b252edbe070a9de8501eef63c17ef5
- https://git.kernel.org/stable/c/ac9fe7dd8e730a103ae4481147395cc73492d786
- https://git.kernel.org/stable/c/e5bee633cc276410337d54b99f77fbc1ad8801e5
References
- https://git.kernel.org/stable/c/295f7c579b07b5b7cf2dffe485f71cc2f27647cb
- https://git.kernel.org/stable/c/2c928b3a0b04a431ffcd6c8b7d88a267124a3a28
- https://git.kernel.org/stable/c/2f2190ce4ca972051cac6a8d7937448f8cb9673c
- https://git.kernel.org/stable/c/39ed887b1dd2d6b720f87e86692ac3006cc111c8
- https://git.kernel.org/stable/c/4e38eaaabfb7fffbb371a51150203e19eee5d70e
- https://git.kernel.org/stable/c/6672e6c00810056acaac019fe26cdc26fee8a66c
- https://git.kernel.org/stable/c/a0ec22fa20b252edbe070a9de8501eef63c17ef5
- https://git.kernel.org/stable/c/ac9fe7dd8e730a103ae4481147395cc73492d786
- https://git.kernel.org/stable/c/e5bee633cc276410337d54b99f77fbc1ad8801e5
- https://syst3mfailure.io/rbtree-family-drama/
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://syst3mfailure.io/rbtree-family-drama/