CVE-2021-24031: facebook zstandard Insecure Inherited Permissions
Vulnerability summary
CVE-2021-24031 is a medium (CVSS 5.5) Insecure Inherited Permissions vulnerability in facebook zstandard. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 38.9% of scored vulnerabilities. 2 public exploits are recorded.
Advisory lineage
Upstream 0 · Downstream 4 · Related 4Timeline
- 04-03-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
In the Zstandard command-line utility prior to v1.4.1, output files were created with default permissions. Correct file permissions (matching the input) would only be set at completion time. Output files could therefore be readable or writable to unintended parties.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
EPSS trend
Probability
0.46%
Chance of exploitation in the next 30 days
Percentile
39%
Versus all other CVEs
30-day change
+0.03 pp
From 0.43% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
2 foundZstd
Maturity: poc
Exploit Reference (bugs.debian.org)
Maturity: unknown
Weaknesses
CWE · root causeAffected systems
Alpine1 product
- zstd< 1.4.1-r0
Debian1 product
- libzstd< 1.4.8+dfsg-1 | < 1.3.8+dfsg-3+deb10u1 | < 1.1.2-1+deb9u1
Facebook1 product
- zstandard≥ unspecified, < 1.4.1 | < 1.4.1
Mageia1 product
- zstd< 1.4.0-1.1.mga7
Ubuntu1 product
- libzstd< 1.3.1+dfsg-1~ubuntu0.16.04.1+esm3 | < 1.3.3+dfsg-2ubuntu1.2 | < 1.4.4+dfsg-3ubuntu0.1
5 vendors · 5 products
References
11 links
bugs.debian.org/cgi-bin/bugreport.cgi?bug=981404X Refsource MISCExploitIssue TrackingMailing ListThird Party Advisory