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7.1
HIGH CVSS 3.1
CVE-2020-36791
net_sched: keep alloc_hash updated after hash allocation
Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: keep alloc_hash updated after hash allocation In commit 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex") I moved cp->hash calculation before the first tcindex_alloc_perfect_hash(), but cp->alloc_hash is left untouched. This difference could lead to another out of bound access. cp->alloc_hash should always be the size allocated, we should update it after this tcindex_alloc_perfect_hash().

INFO

Published Date :

May 7, 2025, 2:15 p.m.

Last Modified :

Nov. 10, 2025, 5:34 p.m.

Remotely Exploit :

No

Source :

416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products

The following products are affected by CVE-2020-36791 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Linux linux_kernel
: Total Affected Vendor : 1 | Products : 1
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH [email protected]
Solution
Update the Linux kernel to address an out-of-bounds access vulnerability in net_sched.
  • Update the Linux kernel to the latest version.
  • Apply the patch for commit 599be01ee567.
  • Ensure cp->alloc_hash is updated correctly.
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2020-36791.

URL Resource
https://blog.cdthoughts.ch/2021/03/16/syzbot-bug.html Third Party Advisory
https://git.kernel.org/stable/c/0d1c3530e1bd38382edef72591b78e877e0edcd3 Patch
https://git.kernel.org/stable/c/557d015ffb27b672e24e6ad141fd887783871dc2 Patch
https://git.kernel.org/stable/c/9f8b6c44be178c2498a00b270872a6e30e7c8266 Patch
https://git.kernel.org/stable/c/bd3ee8fb6371b45c71c9345cc359b94da2ddefa9 Patch
https://git.kernel.org/stable/c/c4453d2833671e3a9f6bd52f0f581056c3736386 Patch
https://git.kernel.org/stable/c/d23faf32e577922b6da20bf3740625c1105381bf Patch
https://git.kernel.org/stable/c/d6cdc5bb19b595486fb2e6661e5138d73a57f454 Patch
https://syzkaller.appspot.com/bug?id=ea260693da894e7b078d18fca2c9c0a19b457534 Issue Tracking
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2020-36791 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2020-36791 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2020-36791 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2020-36791 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Nov. 10, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
    Added CWE CWE-125
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:5.6:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.6:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.6:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.6:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.6:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.6:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.4.214 up to (excluding) 4.4.218 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.9.214 up to (excluding) 4.9.218 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.14.171 up to (excluding) 4.14.175 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.19.103 up to (excluding) 4.19.114 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.4.19 up to (excluding) 5.4.29 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5.3 up to (excluding) 5.5.14 *cpe:2.3:o:linux:linux_kernel:5.6:rc7:*:*:*:*:*:*
    Added Reference Type kernel.org: https://blog.cdthoughts.ch/2021/03/16/syzbot-bug.html Types: Third Party Advisory
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/0d1c3530e1bd38382edef72591b78e877e0edcd3 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/557d015ffb27b672e24e6ad141fd887783871dc2 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/9f8b6c44be178c2498a00b270872a6e30e7c8266 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/bd3ee8fb6371b45c71c9345cc359b94da2ddefa9 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/c4453d2833671e3a9f6bd52f0f581056c3736386 Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/d23faf32e577922b6da20bf3740625c1105381bf Types: Patch
    Added Reference Type kernel.org: https://git.kernel.org/stable/c/d6cdc5bb19b595486fb2e6661e5138d73a57f454 Types: Patch
    Added Reference Type kernel.org: https://syzkaller.appspot.com/bug?id=ea260693da894e7b078d18fca2c9c0a19b457534 Types: Issue Tracking
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    May. 07, 2025

    Action Type Old Value New Value
    Added Reference https://blog.cdthoughts.ch/2021/03/16/syzbot-bug.html
    Added Reference https://syzkaller.appspot.com/bug?id=ea260693da894e7b078d18fca2c9c0a19b457534
  • New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    May. 07, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: net_sched: keep alloc_hash updated after hash allocation In commit 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex") I moved cp->hash calculation before the first tcindex_alloc_perfect_hash(), but cp->alloc_hash is left untouched. This difference could lead to another out of bound access. cp->alloc_hash should always be the size allocated, we should update it after this tcindex_alloc_perfect_hash().
    Added Reference https://git.kernel.org/stable/c/0d1c3530e1bd38382edef72591b78e877e0edcd3
    Added Reference https://git.kernel.org/stable/c/557d015ffb27b672e24e6ad141fd887783871dc2
    Added Reference https://git.kernel.org/stable/c/9f8b6c44be178c2498a00b270872a6e30e7c8266
    Added Reference https://git.kernel.org/stable/c/bd3ee8fb6371b45c71c9345cc359b94da2ddefa9
    Added Reference https://git.kernel.org/stable/c/c4453d2833671e3a9f6bd52f0f581056c3736386
    Added Reference https://git.kernel.org/stable/c/d23faf32e577922b6da20bf3740625c1105381bf
    Added Reference https://git.kernel.org/stable/c/d6cdc5bb19b595486fb2e6661e5138d73a57f454
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 7.1
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact