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CVE-2026-54897· NVD / CVE Program· CNA GitHub_M

Oj : Use-After-Free in Oj::Doc Iterators via Reentrant Close

Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to 3.17.2, Oj::Doc iterators (each_value, each_child, each_leaf) were vulnerable to a heap use-after-free. When a Ruby block yielded during iteration calls doc.close or d.close, the document's heap memory is freed while the C iterator is still running. When control returns from the block, the iterator reads from the freed region, producing a use-after-free accessible from pure Ruby. This issue has been fixed in version 3.17.2.

LowCVSS 2.1 · v4.0—No exploit Fix available
Published
Jun 30, 2026
Updated
Jul 1, 2026
EPSS
0.1% · 3th percentile
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Report tools

JSON

Action score

8

Monitor

Low priority for now.

CVSS
8 / 40 · 2.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
2.1
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Noroxi analysis

No Noroxi analysis for this record yet

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Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • ohler55 oj

    • < 3.17.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12ruby-ojbefore 3.14.2-1+deb12u13.14.2-1+deb12u1
Debian:13ruby-ojbefore 3.16.3-1+deb13u13.16.3-1+deb13u1
Debian:14ruby-ojbefore 3.17.3-13.17.3-1
RubyGemsojbefore 3.17.33.17.3

Same product

ohler55: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-54592Oj: Stack Buffer Overflow in Oj::Doc#each_child via Deeply Nested Input
    30Monitor
  • CVE-2026-54903Oj: Integer Overflow in Oj.load 2GB String Handling
    25Monitor
  • CVE-2026-54902Oj: Use-After-Free in Oj::Parser SAJ Long Key Callback
    25Monitor
  • CVE-2026-54901Oj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking
    25Monitor
  • CVE-2026-54900Oj: Negative-Size memcpy in Oj::Parser create_id Attribute Handling
    25Monitor
  • CVE-2026-54899Oj: Use-After-Free in Oj::Parser Symbol Key Cache Toggle
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
ohler55 oj3.17.2 · descriptionVendor (CNA)
debian:ruby-oj3.14.2-1+deb12u1 · Debian:12Package registry (OSV)
debian:ruby-oj3.16.3-1+deb13u1 · Debian:13Package registry (OSV)
RubyGems:oj3.17.3Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-548990 days apartOj: Use-After-Free in Oj::Parser Symbol Key Cache Toggle
    25Monitor
  • CVE-2026-549010 days apartOj: Use-After-Free in Oj::Parser array_class/hash_class GC Marking
    25Monitor
  • CVE-2026-549020 days apartOj: Use-After-Free in Oj::Parser SAJ Long Key Callback
    25Monitor
  • CVE-2026-548980 days apartOj: Use-After-Free in Oj::Parser SAJ Callback via Input Mutation
    8Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:4.0/AV:L/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

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records