CVE-2023-40890
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 · uneditedA stack-based buffer overflow vulnerability exists in the lookup_sequence function of ZBar 0.23.90. Specially crafted QR codes may lead to information disclosure and/or arbitrary code execution. To trigger this vulnerability, an attacker can digitally input the malicious QR code, or prepare it to be physically scanned by the vulnerable scanner.
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 · moderate confidenceA stack-based buffer overflow vulnerability exists in the lookup_sequence function of ZBar 0.23.90 QR code library. When processing specially crafted QR codes, the function fails to properly validate input length before copying data into a fixed-size stack buffer, allowing an attacker to overflow the buffer. This can lead to information disclosure via stack memory leakage and/or arbitrary code execution by overwriting return addresses.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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= 0.23.90CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Locate ZBar library installationSearch for ZBar library files on the system - common paths include /usr/lib/, /usr/local/lib/, or embedded within application directories. Look for files named libzbar.so (Linux), libzbar.dylib (macOS), or zbar.dll (Windows).Affected if ZBar library files are found on the system
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Determine installed ZBar versionUse system tools to query the library version: on Linux run 'dpkg -l | grep zbar' or 'rpm -qa | grep zbar', or use 'strings libzbar.so | grep -i version'. Check the library's metadata or version information embedded in the binary.Affected if The installed version is 0.23.90 exactly, or if version detection is ambiguous but the library matches the ZBar 0.23.90 release
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Identify applications using ZBar QR scanningAudit running processes or recently executed applications that process QR codes or barcode images. Search application logs, dependencies, or configuration for ZBar library usage. Review any software that imports or links against libzbar.Affected if Any application or service uses ZBar to process QR codes from untrusted sources
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Verify QR code processing is activeIf ZBar is embedded in a custom application, review the application code to confirm it invokes the lookup_sequence function path. Check if the application accepts QR code input from external or network sources.Affected if The lookup_sequence function in ZBar is invoked during QR code processing operations
The environment is affected if ZBar version 0.23.90 is installed and any application uses it to process QR codes, since the overflow occurs during QR code data processing in the lookup_sequence function.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataUpgrade to a patched version of ZBar when available. Until then, implement input validation on QR code data before processing, restrict QR code input sources to trusted origins, and consider isolating QR scanning functionality in sandboxed environments to limit exploitation impact.
- Consultation6.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-40890 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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