{"cve":"CVE-2021-47125","nvd":{"published":"2024-03-15T21:15:07.307","modified":"2026-06-17T04:16:35.013","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsch_htb: fix refcount leak in htb_parent_to_leaf_offload\n\nThe commit ae81feb7338c (\"sch_htb: fix null pointer dereference\non a null new_q\") fixes a NULL pointer dereference bug, but it\nis not correct.\n\nBecause htb_graft_helper properly handles the case when new_q\nis NULL, and after the previous patch by skipping this call\nwhich creates an inconsistency : dev_queue->qdisc will still\npoint to the old qdisc, but cl->parent->leaf.q will point to\nthe new one (which will be noop_qdisc, because new_q was NULL).\nThe code is based on an assumption that these two pointers are\nthe same, so it can lead to refcount leaks.\n\nThe correct fix is to add a NULL pointer check to protect\nqdisc_refcount_inc inside htb_parent_to_leaf_offload.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/2411c02d03892a5057499f8102d0cc1e0f852416","https://git.kernel.org/stable/c/944d671d5faa0d78980a3da5c0f04960ef1ad893","https://git.kernel.org/stable/c/2411c02d03892a5057499f8102d0cc1e0f852416","https://git.kernel.org/stable/c/944d671d5faa0d78980a3da5c0f04960ef1ad893"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:46:54.846886191+00:00"},"epss":{"cve":"CVE-2021-47125","score":0.00193,"percentile":0.09073,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}