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Review reviewHigh

CVE-2021-47107

Linux Linux, SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, linux kernel

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 arithmet...

CVSS
7.8
EPSS
-
- percentile
CISA KEV
Not listed
Published
2024.03.05
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.8

Vulnerability overview

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 arithmet...

Affected product and versions

Product
Linux Linux, SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, linux kernel
Affected versions
>= 37aa5e64022243e721b8334122997881177a4cfc < 9e291a6a28d32545ed2fd959a8165144d1724df1, >= 7f87fc2d34d475225e78b7f5c4eabb121f4282b2 < eabc0aab98e5218ceecd82069b0d6fdfff5ee885, >= 7f87fc2d34d475225e78b7f5c4eabb121f4282b2 < 53b1119a6e5028b125f431a0116ba73510d82a72, >= 5.13, >= 5.13 < 5.15.12, 5.16
Fixed versions
5.15.12

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-120