CVE-2025-38001

Advisory lineage Upstream: 0 Downstream: 137
Modified
Published: 06 Jun 2025, 13:41
Last modified:11 May 2026, 21:19

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.03% LOW
0% probability +0.02%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

06 Jun 2025, 13:41
Published
Vulnerability first disclosed
11 May 2026, 21:19
Last Modified
Vulnerability information updated

Description

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

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.03%• Percentile: 8%

Techniques & Countermeasures

  • CWE-835•Loop with Unreachable Exit Condition ('Infinite Loop')

    The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Affected Systems

  • debian•debian_linux

    11.0 | 12.0

  • linux•linux

    ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < e5bee633cc276410337d54b99f77fbc1ad8801e5 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 6672e6c00810056acaac019fe26cdc26fee8a66c | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 2c928b3a0b04a431ffcd6c8b7d88a267124a3a28 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < a0ec22fa20b252edbe070a9de8501eef63c17ef5 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 295f7c579b07b5b7cf2dffe485f71cc2f27647cb | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 2f2190ce4ca972051cac6a8d7937448f8cb9673c | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 4e38eaaabfb7fffbb371a51150203e19eee5d70e | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 39ed887b1dd2d6b720f87e86692ac3006cc111c8 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < ac9fe7dd8e730a103ae4481147395cc73492d786 | 5.0

  • linux•linux_kernel

    ≥ 5.0.1, < 5.4.294 | ≥ 5.5, < 5.10.238 | ≥ 5.11, < 5.15.185 | ≥ 5.16, < 6.1.141 | ≥ 6.2, < 6.6.93 | ≥ 6.7, < 6.12.32 | ≥ 6.13, < 6.14.10 | ≥ 6.15, < 6.15.1 | 5.0 | 5.0:rc3 | 5.0:rc4 | 5.0:rc5 | 5.0:rc6 | 5.0:rc7 | 5.0:rc8

References (12)