dbcve.org
FedoraOperating system · Fedoraproject

CVE-2021-42716

HIGH · 7.1 CVSS v3.1 Published 2021-10-21
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
74/100
Remediation priority · Elevated
Public exploit No privileges Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue was discovered in stb stb_image.h 2.27. The PNM loader incorrectly interpreted 16-bit PGM files as 8-bit when converting to RGBA, leading to a buffer overflow when later reinterpreting the result as a 16-bit buffer. An attacker could potentially have crashed a service using stb_image, or read up to 1024 bytes of non-consecutive heap data without control over the read location.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-120

A fixed-size buffer is filled without checking the length of the incoming data, so it overflows into neighbouring memory. This is the classic overflow attackers use to overwrite return addresses and hijack execution. The fix is strict length checks and safe, bounded string and memory functions.

General guidance for the classic buffer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 33= 34= 35
Stb Image.hApplication
Affected:= 2.27

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix High confidence

stb_image.h version 2.28 or later (or latest master branch after PR #1223 was merged)

  1. 1. Locate the stb_image.h file in your project (likely in a vendor/ or third-party/ directory)
  2. 2. Check the current version by searching for 'stb_image.h v2.27' or similar version string at the top of the file
  3. 3. Download the latest version of stb_image.h from https://github.com/nothings/stb/blob/master/stb_image.h
  4. 4. Verify the fix from PR #1223 is included by checking the PNM loading code handles 16-bit PGM files correctly
  5. 5. Replace the existing stb_image.h with the updated version
  6. 6. Rebuild and test your application to confirm the vulnerability is resolved
  7. 7. If you cannot upgrade, manually apply the fix from https://github.com/nothings/stb/pull/1223 to your local copy of stb_image.h
Caveat stb_image.h is a single-header library with no external dependencies; the upgrade should not break existing code as the fix is a bug correction, not an API change

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-42716 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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