CVE-2017-11608
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 · uneditedThere is a heap-based buffer over-read in the Sass::Prelexer::re_linebreak function in lexer.cpp in LibSass 3.4.5. A crafted input will lead to a remote denial of service attack.
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 confidenceLibSass 3.4.5 contains a heap-based buffer over-read vulnerability in the Sass::Prelexer::re_linebreak function in lexer.cpp. When processing crafted Sass input, the function reads beyond the allocated buffer boundary on the heap, leading to potential memory corruption and 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= 3.4.5CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/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 installed LibSass versionRun 'libsass-version' command, check package manager (npm list libsass, pip show libsass, or gem list libsass), or inspect compiled binary with 'strings' grep for '3.4.5'Affected if The installed version is exactly 3.4.5
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Locate the LibSass lexer.cpp fileSearch for lexer.cpp in the LibSass installation directory, commonly found in node_modules/libsass/src/lexers/ or /usr/include/libsass/ or the source code directoryAffected if lexer.cpp exists and its modification date corresponds to version 3.4.5
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Verify the re_linebreak function presenceOpen lexer.cpp and search for 're_linebreak' function definition using grep 're_linebreak' or by inspecting the file directlyAffected if The function exists in the codebase, indicating the vulnerable component is present
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Determine if application processes Sass inputReview application code for LibSass API usage (e.g., sass_compile, sass_compile_file, or sass2scss) or check if .scss/.sass files are processedAffected if The application uses LibSass to compile Sass input, enabling the vulnerable code path
You are affected if LibSass version 3.4.5 is installed and your application processes Sass input using the vulnerable lexer component.
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 dataUpdate LibSass to a version newer than 3.4.5 that includes the fix for this buffer over-read. If immediate updating is not feasible, implement input validation and length checking on Sass input before processing.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-11608 — 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-2017-11608 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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