CVE-2026-54900
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 · uneditedOj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in usual mode with create_id enabled, Oj::Parser#parse is vulnerable to heap corruption via a negative-size memcpy. When a JSON object key is exactly 65,535 bytes long, an integer truncation in form_attr (usual.c:63) converts the length to -1 before passing it to memcpy. This causes memcpy to copy SIZE_MAX bytes (interpreted as a huge size_t), corrupting heap memory and crashing the process. The issue has been fixed in version 3.17.2.
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 confidenceIn Oj versions prior to 3.17.2, when using usual mode with create_id enabled, the parser suffers from integer truncation in form_attr (usual.c:63). When a JSON object key is exactly 65,535 bytes long, the length value truncates to -1, which memcpy interprets as SIZE_MAX, causing heap corruption and process crash.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- Authentication
- X
- User interaction
- None
- Scope
- X
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
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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Check Oj gem versionRun `gem list oj` or `ruby -e "require 'oj'; puts Oj::VERSION"`Affected if Version is lower than 3.17.2
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Identify if Oj usual mode is in useSearch codebase for `Oj.load` or `Oj.parse` calls with options containing `:mode => :usual` or default mode behavior. Check if Oj is loaded without explicit mode specification (defaults to :object mode, not :usual)Affected if Code explicitly sets `:mode => :usual` or relies on :usual as default in older versions
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Verify create_id is enabledSearch for Oj options containing `:create_id =>` or check if ` Oj.default_options[:create_id]` is set (commonly set to 'json_class' or similar)Affected if create_id is explicitly set to a non-nil value (commonly 'json_class')
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Check for JSON processing with potentially large object keysReview JSON input sources for any that could contain object keys approaching 65,535 bytes in length. Monitor application logs for crashes occurring during JSON parsing of objects with long keysAffected if Application processes JSON where object keys could be exactly 65,535 bytes long while using affected Oj configuration
Affected if running Oj gem version below 3.17.2 with usual mode enabled, create_id set, and processing JSON with object keys reaching exactly 65,535 bytes.
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 Oj gem to version 3.17.2 or later to resolve the heap corruption vulnerability.
3.17.2
- Check the current installed version of the Oj gem by running: gem list oj
- Update the Oj gem to version 3.17.2 by running: gem install oj -v 3.17.2
- If using Bundler, update the Gemfile to specify: gem 'oj', '~> 3.17', '>= 3.17.2' and run: bundle update oj
- Verify the installed version is 3.17.2 or later by running: gem list oj
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 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 $1,376.
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Free · runs locallyCheck whether your project pulls in CVE-2026-54900 — 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-2026-54900 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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