CVE-2021-34123
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 · uneditedAn issue was discovered on atasm, version 1.09. A stack-buffer-overflow vulnerability in function aprintf() in asm.c allows attackers to execute arbitrary code on the system via a crafted file.
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 · high confidenceA stack-buffer-overflow vulnerability exists in the aprintf() function in asm.c of atasm assembler version 1.09. The function does not properly validate the size of data being written to a stack-allocated buffer, allowing an attacker to overwrite adjacent memory by supplying a crafted assembly source file. This can lead to arbitrary code execution.
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= 1.09CVSS 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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Verify Atasm installationCheck if theatasm assembler is present on the system by running 'which atasm' or searching common binary directories such as /usr/bin/atasm, /usr/local/bin/atasm, or checking the PATH.Affected if atasm binary exists on the system
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Determine installed Atasm versionRun 'atasm --version' or 'atasm -v' to retrieve the version number. Alternatively, check the source code or package metadata if installed from source or a package manager.Affected if version returned is 1.09 exactly
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Identify asm.c source fileLocate the asm.c source file in the atasm installation directory or source tree. Search for files named asm.c that contain the aprintf() function.Affected if asm.c file exists and contains the aprintf() function definition
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Inspect aprintf() function implementationExamine the aprintf() function in asm.c for lack of bounds checking. Look for string operations (such as sprintf, strcpy, or similar) writing to stack-allocated buffers without size validation.Affected if aprintf() writes to a stack buffer without size limits or validation checks
The environment is affected if atasm version 1.09 is installed and the aprintf() function in asm.c lacks proper buffer size validation.
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 dataReplace unsafe string operations in aprintf() with bounds-checked functions (e.g., snprintf) and add input validation for data written to stack buffers. Alternatively, update to a patched version if available.
- Consultation3.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-34123 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
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-2021-34123 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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