Vulnerability in Linux

CVE-2021-47125

In the Linux kernel, the following vulnerability has been resolved: sch_htb: fix refcount leak in htb_parent_to_leaf_offload The commit ae81feb7338c ("sch_htb: fix null pointer dereference on a null new_q") fixes a NULL pointer dereference bug, but it is not correct. Because htb_graft_helper properly handles the case when new_q is NULL, and after the previous patch by skipping this call which creates an inconsistency : dev_queue->qdisc will still point to the old qdisc, but cl->parent->leaf.q will point to the new one (which will be noop_qdisc, because new_q was NULL). The code is based on an assumption that these two pointers are the same, so it can lead to refcount leaks. The correct fix is to add a NULL pointer check to protect qdisc_refcount_inc inside htb_parent_to_leaf_offload.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (8.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 8.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2021-47125: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Linux — versions ae81feb7338c89cee4e6aa0424bdab2ce2b52da2, 5.12, 0
  • Linux Kernel — versions 5.13

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2021-47125?
CVE-2021-47125 is a medium-severity vulnerability in Linux. CVSS score: 5.5/10. Published 2024-03-15.
How severe is CVE-2021-47125?
Medium severity. CVSS v3 base score is 5.5 out of 10.
Is CVE-2021-47125 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.