CVE-2018-6551
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 · uneditedThe malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386, did not properly handle malloc calls with arguments close to SIZE_MAX and could return a pointer to a heap region that is smaller than requested, eventually leading to heap corruption.
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 confidenceThe malloc implementation in glibc versions 2.24-2.26 on powerpc and 2.26 on i386 fails to properly handle allocation requests with sizes close to SIZE_MAX, returning pointers to undersized heap regions which leads to heap corruption and potential 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>= 2.24, <= 2.26CVSS 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:3.0/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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Identify glibc versionRun `ldd --version` or check `/lib/libc.so.6 --version` to obtain the installed glibc version numberAffected if The version displayed is 2.24, 2.25, or 2.26 (versions 2.24 through 2.26 are affected)
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Confirm system architectureRun `uname -m` or `arch` to identify the system processor architectureAffected if The architecture is powerpc/powerpc64 or i386/i686 (the flaw only affects powerpc in versions 2.24-2.26, and i386 in version 2.26)
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Cross-reference version and architectureCombine the results from step 1 and step 2: if on powerpc with glibc 2.24-2.26, or on i386 with glibc 2.26, the system falls within the affected configurationAffected if The architecture is powerpc/powerpc64 AND glibc version is between 2.24 and 2.26 inclusive, OR the architecture is i386/i686 AND glibc version is exactly 2.26
A system is affected if it runs on powerpc or i386 architecture with a glibc version in the range 2.24-2.26 (with i386 only affected at version 2.26 specifically).
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 · scopedUpgrade glibc to version 2.27 or later where the malloc implementation properly handles large allocation requests, or apply distribution-provided security patches.
glibc 2.27 or later
- Identify current glibc version using `ldd --version` or `rpm -q glibc` (RHEL/CentOS) or `dpkg -l | grep libc6` (Debian/Ubuntu)
- Update glibc package: On RHEL/CentOS use `yum update glibc` or `dnf update glibc`
- On Debian/Ubuntu use `apt-get update && apt-get install libc6` or `apt-get upgrade`
- Restart all services or reboot the system to ensure the new glibc library is loaded into memory
- Verify the upgrade was successful by checking glibc version again with `ldd --version` - should show 2.27 or later
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-6551 — 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-2018-6551 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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