CVE-2021-27419
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 · unediteduClibc-ng versions prior to 1.0.37 are vulnerable to integer wrap-around in functions malloc-simple. This improper memory assignment can lead to arbitrary memory allocation, resulting in unexpected behavior such as a crash or a remote code injection/execution.
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 confidenceuClibc-ng versions before 1.0.37 contain an integer wrap-around vulnerability in malloc-simple functions. This flaw allows improper memory assignment through integer overflow, enabling attackers to manipulate memory allocation sizes and potentially achieve remote 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< 1.0.37CVSS 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 uclibc-ng library on the systemSearch for libuclibc or uclibc files in common library directories: find /lib /usr/lib /lib64 -name '*uclibc*' 2>/dev/null. Also check if it is provided by a package manager: dpkg -l | grep uclibc or rpm -qa | grep uclibcAffected if No uclibc-ng library is found in the environment, then this CVE does not apply
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Determine installed uclibc-ng versionIf found as a package, query its version: dpkg -l <package_name> or rpm -qi <package_name>. If the library file exists, check for version strings: strings <path_to_library> | grep -i version or readelf -d <path_to_library> | grep VERSIONAffected if The installed version is any version before 1.0.37, including unknown versions that cannot be confirmed as 1.0.37 or later
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Identify if malloc-simple functions are in useSearch application source code or binaries for calls to malloc-simple related functions. Use: grep -r "malloc.simple\|malloc_simple" /path/to/source or objdump -T /path/to/binary | grep mallocAffected if The application or system uses malloc-simple implementation from uclibc-ng and the uclibc-ng version is below 1.0.37
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Check for integer overflow conditions in allocation requestsReview application code that passes size values to malloc functions. Look for calculations where size values are derived from user input or untrusted sources without proper bounds checking before calling mallocAffected if Applications perform memory allocation with size values that could wrap around due to integer overflow, combined with a vulnerable uclibc-ng version
The environment is affected if uclibc-ng version is confirmed below 1.0.37 AND the system or any application uses malloc-simple functions with size values that could trigger integer wrap-around.
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.
dbcve · scoped1.0.37
Upgrade uClibc-ng to version 1.0.37 or later to patch the integer wrap-around vulnerability in malloc-simple.
uclibc-ng 1.0.37
- Identify the current version of uclibc-ng in your environment by checking your build system, package manager, or firmware components
- Obtain uclibc-ng version 1.0.37 or later from the official source at downloads.uclibc-ng.org
- Rebuild your application, system image, or firmware with the updated uclibc-ng library
- Test the updated system to ensure compatibility with the new library version
- Redeploy the updated system image or firmware to all affected devices
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation6.0 h
- Implementation12.0 h
- Testing10.0 h
- Review / QA5.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,216.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27419 — 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-2021-27419 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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