VulnerabilityPublished 1 Jul 2026

CVE-2026-54500: Out-of-bounds Read in ohler55 oj

Affects ojSource GCVE Database

Not known to be exploited : upgrade to 3.17.3 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.1% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.17.3

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade oj to 3.17.3.

Affected software

Product	Affected	Fixed in
RubyGemsoj`pkg:gem/oj`Other threats	Affected <3.17.3	Fixed in 3.17.3
Ubuntu 14.04 LTSruby-oj`pkg:deb/ubuntu/ruby-oj?arch=source&distro=trusty`Other threats	Affected 2.0.10-1 – 2.5.3-1 4 affected builds	Fixed in–
Ubuntu 16.04 LTSruby-oj`pkg:deb/ubuntu/ruby-oj?arch=source&distro=xenial`Other threats	Affected 2.12.10-3 – 2.12.10-4build1 4 affected builds	Fixed in–
Ubuntu 18.04 LTSruby-oj`pkg:deb/ubuntu/ruby-oj?arch=source&distro=bionic`Other threats	Affected =2.17.4-1 =3.4.0-1 =3.4.0-1build1	Fixed in–
Ubuntu 20.04 LTSruby-oj`pkg:deb/ubuntu/ruby-oj?arch=source&distro=focal`Other threats	Affected 3.8.1-1 – 3.10.1-1build1 5 affected builds	Fixed in–
Ubuntu 22.04 LTSruby-oj`pkg:deb/ubuntu/ruby-oj?arch=source&distro=jammy`Other threats	Affected 3.11.0-1 – 3.13.9-1build1 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Oj to version 3.17.3 or later, where this vulnerability is fixed. No other mitigations are indicated or required.

Description

CVE-2026-54500 is a vulnerability in the Oj Ruby gem used for JSON parsing and object marshalling. Versions prior to 3.17.3 have an out-of-bounds read flaw in the Oj.load function when processing JSON objects with keys of 254 bytes or longer. This can lead to uninitialized stack memory being read and potentially disclosed via interned symbols or error messages. The issue is fixed in version 3.17.3.

Impact

Exploitation of this vulnerability can lead to disclosure of uninitialized stack memory contents, potentially exposing sensitive information. There is no indication of remote code execution or denial of service. No known exploits are reported in the wild.

Summary

The vulnerability in Oj (Optimized JSON) Ruby gem arises from an out-of-bounds read in the Oj.load function when handling JSON keys of 254 bytes or more. This flaw allows reading uninitialized stack memory, which may result in unintended information disclosure through interned symbols or error messages. The defect is addressed in version 3.17.3, which eliminates the out-of-bounds read condition.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-908Use of Uninitialized Resource (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product uses or accesses a resource that has not been initialized.
Implementation
Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.
Implementation
Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
Implementation
Avoid race conditions (CWE-362) during initialization routines.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 25 Oct 2026, 23:23 UTC

WeaknessesCWE-125, CWE-908

Technical details

References

Community reviews

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