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TI-2026-39346 Aliases CVE-2026-54500GHSA-fm7p-mprw-wjm9

Oj: intern.c form_attr has an uninitialized stack read

Priority LOW 29CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-125 and the CVSS impact.

Summary

Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.3, Oj.load in :object mode reads uninitialized stack memory (and, for long keys, reads out of bounds) when parsing a JSON object whose key is 254 bytes or longer. The interned bytes can surface to the caller, disclosing process stack memory. In ext/oj/intern.c, form_attr() handles the long-key path by allocating a heap buffer, `b`, populating it with the attribute name, and then freeing it — but it passed the uninitialized stack buffer buf (not b) to rb_intern3(). rb_intern3 therefore reads len + 1 bytes of uninitialized stack memory. When the key length is >= 256, it also reads out of bounds past the 256-byte buf. The resulting bytes are interned and can reach the caller via the produced Symbol or via the EncodingError message raised on invalid UTF-8, leaking process stack contents. This issue has been fixed in version 3.17.3.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00198 9th percentileScored 2026-11-07
Fix Fixed oj (ohler55): 3.17.3oj (RubyGems): 3.17.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ohler55ojbefore 3.17.33.17.3Patch availableCNA
—oj (RubyGems)before 3.17.33.17.3Patch availableGHSA-fm7p-mprw-wjm9
  • oj Vendorohler55 Affected before 3.17.3 Fixed in 3.17.3 Patch available CNA
  • oj (RubyGems) Vendor— Affected before 3.17.3 Fixed in 3.17.3 Patch available GHSA-fm7p-mprw-wjm9

Remediation

  • Fix · CNA oj (ohler55) Fixed in 3.17.3
  • Fix · GHSA-fm7p-mprw-wjm9 oj (RubyGems) Fixed in 3.17.3 Advisory →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-54500
  2. 2026-10-03 Alias added: GHSA-fm7p-mprw-wjm9

References

Other 2

  • TI-2026-39426 Oj: Stack Buffer Overflow in Oj::Doc#each_child via Deeply Nested Input CVSS 3.1HIGH 7.5
  • TI-2026-39672 Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling CVSS 4.0MEDIUM 6.3
  • TI-2026-39348 Oj: Stack Buffer Overflow in Oj.dump via Large Indent CVSS 4.0MEDIUM 6.3
  • TI-2026-39675 Oj: Integer Overflow in Oj.load 2GB String Handling CVSS 4.0MEDIUM 6.3
  • TI-2026-39674 Oj: Use-After-Free in Oj::Parser SAJ Long Key Callback CVSS 4.0MEDIUM 6.3
  • TI-2026-39673 Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking CVSS 4.0MEDIUM 6.3
See all 10 →

Sources

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