PT-2024-8990 · Linux+3 · Linux Kernel+3

Hangbin Liu · Published 2024-05-24 · Updated 2025-07-28 · CVE-2021-47557

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions: Linux kernel versions prior to 5.16.0-rc1+ #475

Description: The issue is related to a NULL pointer dereference in the Linux kernel's sch ets component. When the number of DRR classes decreases, the round-robin active list can contain elements that have already been freed in ets qdisc change(), leading to a NULL dereference crash. This is caused by the attempt to call cl->qdisc->ops->peek(cl->qdisc) when cl->qdisc is NULL.

Recommendations: At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

NULL Pointer Dereference

Weakness Enumeration

CWE-476

Related Identifiers

BDU:2024-10672

CVE-2021-47557

OPENSUSE-SU-2024_2185-1

SUSE-SU-2024:2008-1

SUSE-SU-2024:2010-1

SUSE-SU-2024:2019-1

SUSE-SU-2024:2185-1

SUSE-SU-2024:2190-1

SUSE-SU-2025:02264-1

SUSE-SU-2025:02321-1

SUSE-SU-2025:02322-1

SUSE-SU-2025:02537-1

SUSE-SU-2025:2264-1

SUSE-SU-2025_02264-1

SUSE-SU-2025_02537-1

Affected Products

Astra Linux

Linux Kernel

Red Os

Suse

References · 1938

• 🔥 https://github.com/lanleft/CVE-2023-1829 · Exploit
• 🔥 https://github.com/aels/CVE-2022-2586-LPE · Exploit
• 🔥 https://github.com/sniper404ghostxploit/CVE-2022-2586 · Exploit
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47557 · Vendor Advisory
• https://git.kernel.org/stable/c/ae2659d2c670252759ee9c823c4e039c0e05a6f2 · Patch
• https://osv.dev/vulnerability/SUSE-SU-2025:02264-1 · Vendor Advisory
• https://git.kernel.org/stable/c/e25bdbc7e951ae5728fee1f4c09485df113d013c · Patch
• https://git.kernel.org/stable/c/de6d25924c2a8c2988c6a385990cafbe742061bf · Patch
• https://bdu.fstec.ru/vul/2024-10672 · Security Note
• https://osv.dev/vulnerability/SUSE-SU-2024:2010-1 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2025:02322-1 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-47557 · Security Note
• https://osv.dev/vulnerability/SUSE-SU-2024:2019-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-47557 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2021-47557 · Vendor Advisory