Vulnerability Database

309,364

Total vulnerabilities in the database

CVE-2025-37890

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

net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc

As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case).

This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case.

[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

  • Published: May 16, 2025
  • Updated: Nov 18, 2025
  • CVE: CVE-2025-37890
  • Severity: High
  • Exploit:

CVSS v3:

  • Severity: High
  • Score: 7.8
  • AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWEs:

Software From Fixed in
linux / linux_kernel 5.0.1 5.4.294
linux / linux_kernel 5.5 5.10.238
linux / linux_kernel 5.11 5.15.182
linux / linux_kernel 5.16 6.1.138
linux / linux_kernel 6.2 6.6.90
linux / linux_kernel 6.7 6.12.28
linux / linux_kernel 6.13 6.14.6
linux / linux_kernel 5.0 5.0.x
linux / linux_kernel 5.0-rc3 5.0-rc3.x
linux / linux_kernel 5.0-rc4 5.0-rc4.x
linux / linux_kernel 5.0-rc5 5.0-rc5.x
linux / linux_kernel 5.0-rc6 5.0-rc6.x
linux / linux_kernel 5.0-rc7 5.0-rc7.x
linux / linux_kernel 5.0-rc8 5.0-rc8.x
linux / linux_kernel 6.15-rc1 6.15-rc1.x
linux / linux_kernel 6.15-rc2 6.15-rc2.x
linux / linux_kernel 6.15-rc3 6.15-rc3.x
linux / linux_kernel 6.15-rc4 6.15-rc4.x
debian / debian_linux 11.0 11.0.x