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CVE-2021-46936

7.8 · HIGH

In the Linux kernel, the following vulnerability has been resolved: net: fix use-after-free in tw_timer_handler A real world panic issue was found as follow in Linux 5.4.

Published Feb 27, 2024CWE-416EPSS 0.25%

Overview

CVE-2021-46936 is a high-severity vulnerability. It was published on February 27, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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

net: fix use-after-free in tw_timer_handler

A real world panic issue was found as follow in Linux 5.4.

BUG: unable to handle page fault for address: ffffde49a863de28

PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0

RIP: 0010:tw_timer_handler+0x20/0x40

Call Trace:

<IRQ>

call_timer_fn+0x2b/0x120

run_timer_softirq+0x1ef/0x450

__do_softirq+0x10d/0x2b8

irq_exit+0xc7/0xd0

smp_apic_timer_interrupt+0x68/0x120

apic_timer_interrupt+0xf/0x20

This issue was also reported since 2017 in the thread [1],

unfortunately, the issue was still can be reproduced after fixing

DCCP.

The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net

namespace is destroyed since tcp_sk_ops is registered befrore

ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops

in the list of pernet_list. There will be a use-after-free on

net->mib.net_statistics in tw_ti

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13Refgit.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022Refgit.kernel.org/stable/c/2386e81a1d277f540e1285565c9d41d531bb69d4Refgit.kernel.org/stable/c/5c2fe20ad37ff56070ae0acb34152333976929b4Refgit.kernel.org/stable/c/a8e1944b44f94f5c5f530e434c5eaee787254566Refgit.kernel.org/stable/c/e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0Refgit.kernel.org/stable/c/e73164e89d1be561228a4534e1091369ee4ba41aRefgit.kernel.org/stable/c/fe5838c22b986c1190f1dce9aa09bf6a491c1a69Refgit.kernel.org/stable/c/08eacbd141e2495d2fcdde84358a06c4f95cbb13Refgit.kernel.org/stable/c/15579e1301f856ad9385d720c9267c11032a5022

How CyberStrike helps

Frequently asked questions

What is CVE-2021-46936?

CVE-2021-46936 is a high-severity vulnerability. It was published on February 27, 2024 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2021-46936?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-46936?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-46936?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-46936 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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