CVE-2018-12102
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 · uneditedmd4c 0.2.6 has a NULL pointer dereference in the function md_process_line in md4c.c, related to ctx->current_block.
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 confidencemd4c 0.2.6 contains a NULL pointer dereference vulnerability in the md_process_line function in md4c.c. The issue occurs when accessing ctx->current_block, which can become NULL during Markdown processing. When a specially crafted Markdown document is parsed, this NULL dereference causes a crash, resulting in denial of service.
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= 0.2.6CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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 md4c library versionRun 'pkg-config --modversion md4c' on systems with pkg-config, or check library files in system paths using 'ls -la /usr/lib/libmd4c*' and query the package manager (dpkg -l | grep md4c or rpm -qi md4c)Affected if The installed version resolves to exactly 0.2.6
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Check application dependency declarationsExamine application dependency manifests (package.json, requirements.txt, Cargo.toml, go.mod, Gemfile, etc.) or binary linkage using 'ldd <binary>' to find if md4c is linked and at what versionAffected if Application declares dependency on md4c version 0.2.6 specifically
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Verify markdown processing is in useIdentify whether any deployed application or service uses md4c for parsing Markdown by checking configuration files, code references to md4c functions (md_parse, md_process_line), or monitoring active processes that handle Markdown contentAffected if The application processes Markdown input using the vulnerable md4c library
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Inspect crash logs for md4c crashesReview application error logs, system crash logs (journalctl, dmesg), or core dumps for NULL pointer dereference errors in md_process_line or md4c.cAffected if Crashes occur in md4c parsing code with NULL dereference symptoms
Environment is affected if md4c version 0.2.6 is installed and actively used to process Markdown input, as this specific version contains the NULL pointer dereference in md_process_line when ctx->current_block becomes NULL.
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 md4c if available. If upgrading is not immediately possible, implement input validation to reject malformed Markdown that could trigger the NULL condition, and monitor for crashes in markdown processing workflows.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-12102 — 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-2018-12102 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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