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7.8
HIGH CVSS 3.1
CVE-2021-47107
NFSD: Fix READDIR buffer overflow
Description

In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.

INFO

Published Date :

March 4, 2024, 7:15 p.m.

Last Modified :

Feb. 14, 2025, 3:22 p.m.

Remotely Exploit :

No

Source :

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

The following products are affected by CVE-2021-47107 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
This vulnerability can be resolved by updating the Linux kernel and rebooting the system.
  • Update the affected Linux kernel packages.
  • Reboot the system to apply the update.
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-2021-47107.

URL Resource
https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit Mailing List Patch
https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit Mailing List Patch
https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit Mailing List Patch
https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit Mailing List Patch
https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit Mailing List Patch
https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit Mailing List Patch
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-47107 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-2021-47107 weaknesses.

CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-42: MIME Conversion MIME Conversion CAPEC-44: Overflow Binary Resource File Overflow Binary Resource File CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-92: Forced Integer Overflow Forced Integer Overflow CAPEC-100: Overflow Buffers Overflow Buffers

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-2021-47107 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-2021-47107 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]

    Feb. 14, 2025

    Action Type Old Value New Value
    Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    Added CWE NIST CWE-120
    Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.13 up to (excluding) 5.15.12 *cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.16:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.16:rc6:*:*:*:*:*:*
    Changed Reference Type https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 No Types Assigned https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit, Mailing List, Patch
    Changed Reference Type https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 No Types Assigned https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 Exploit, Mailing List, Patch
    Changed Reference Type https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 No Types Assigned https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit, Mailing List, Patch
    Changed Reference Type https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 No Types Assigned https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 Exploit, Mailing List, Patch
    Changed Reference Type https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 No Types Assigned https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit, Mailing List, Patch
    Changed Reference Type https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 No Types Assigned https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 Exploit, Mailing List, Patch
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72
    Added Reference https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1
    Added Reference https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Jun. 21, 2024

    Action Type Old Value New Value
    Added Reference kernel.org https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 [No types assigned]
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    May. 28, 2024

    Action Type Old Value New Value
  • CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Mar. 04, 2024

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
    Added Reference Linux https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 [No types assigned]
    Added Reference Linux https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 [No types assigned]
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: 7.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact