CVE-2026-54899
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. Prior to version 3.17.2, disabling symbol_keys on a reused Oj::Parser instance triggers a heap use-after-free. When symbol_keys is toggled from true to false, opt_symbol_keys_set frees the internal key cache (cache_free) but does not clear the pointer. The next parse call reads from the freed cache via cache_intern, producing a use-after-free. This 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 confidenceA heap use-after-free vulnerability exists in Oj (Optimized JSON) Ruby gem versions prior to 3.17.2. When symbol_keys is toggled from true to false on a reused Oj::Parser instance, the opt_symbol_keys_set function frees the internal key cache but fails to clear the pointer. Subsequent parse operations then read from the freed cache via cache_intern, triggering the use-after-free.
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:L/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 installed Oj gem versionRun `gem list oj` or in Ruby: `require 'oj'; puts Oj::VERSION`Affected if Version is lower than 3.17.2
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Identify Oj::Parser usageSearch codebase for `Oj::Parser.new` or `Oj.parser` method callsAffected if Code creates Oj::Parser instances that are reused across multiple parse operations
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Check for symbol_keys option togglingSearch for code that sets symbol_keys to true then later changes it to false on the same parser instance, e.g., `parser.symbol_keys = true` followed by `parser.symbol_keys = false`Affected if A reused parser instance has symbol_keys toggled from true to false during its lifecycle
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Verify parser instance reuseLook for parser objects stored in variables and used across multiple method calls or in loopsAffected if The same parser instance is reused for multiple parse operations after toggling symbol_keys
User is affected if running Oj gem version below 3.17.2 and reusing an Oj::Parser instance while toggling the symbol_keys option from true to false.
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 to Oj gem version 3.17.2 or later to remediate this vulnerability.
Oj gem version 3.17.2
- Check current Oj gem version by running `gem list oj` or adding `puts Oj::VERSION` to Ruby code
- Update the Oj gem to version 3.17.2 or later using `gem install oj` or adding `gem 'oj', '~> 3.17'` to Gemfile and running `bundle update oj`
- Verify the upgrade was successful by checking `gem list oj` shows version 3.17.2 or higher
- Test that the vulnerable code path (reusing Oj::Parser with symbol_keys toggled from true to false) no longer triggers the use-after-free
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
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Free · runs locallyCheck whether your project pulls in CVE-2026-54899 — 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-2026-54899 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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