CVE-2021-24032

Local file disclosure via delayed permission restriction

Published Mar 4, 2021 · Updated Aug 3, 2024

Incorrect file permissions in Meta Platforms Zstandard 1.4.1 through 1.4.8 allow local users to read CLI output files. The file-output path creates a destination under the process's default umask and only afterward applies restrictive mode 0600, leaving a race window. A local user who can monitor and open the destination during that window can read its contents before the restriction takes effect.

CVSS severity4.7
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect file permissions in Meta Platforms Zstandard 1.4.1 through 1.4.8 allow local users to read CLI output files. The file-output path creates a destination under the process's default umask and only afterward applies restrictive mode 0600, leaving a race window. A local user who can monitor and open the destination during that window can read its contents before the restriction takes effect.

The record

CVE
CVE-2021-24032
Published
Mar 4, 2021
Updated
Aug 3, 2024
Vendor
Meta Platforms, Inc.
Product
Zstandard
Classifications
CWE-277, CWE-276, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.4.1 <unspecified

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Meta Platforms, Inc. · Zstandardversion=1.4.1 <unspecified

Published CVSS scores

1.9NIST NVDAV:L/AC:M/Au:N/C:P/I:N/A:N
4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-277Insecure Inherited Permissions
CWE-276Incorrect Default Permissions
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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