VulnerabilityPublished 1 Jul 2026

CVE-2026-54897: Use After Free in ohler55 oj

Affects ojSource GCVE Database

Not known to be exploited · fixed in 3.17.2 : patch oj soon.

Data as of 26 Oct 2026, 14:05 UTC

Severity

High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.17.2, 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 3.17.2; oj to 3.17.3.

Affected software

Product	Affected	Fixed in
RubyGemsoj`pkg:gem/oj`Other threats	Affected <3.17.2	Fixed in 3.17.2
RubyGemsoj	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–

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

AI-suggested

A fix is available in versions 3.17.2 and 3.17.3 of the Ruby oj gem. Users should upgrade to these versions or later to remediate this vulnerability.

Description

CVE-2026-54897 is a heap use-after-free vulnerability in the Ruby oj gem (Optimized JSON) versions prior to 3.17.2. The flaw occurs when a Ruby block yields during iteration over Oj::Doc iterators and calls doc.close or d.close, which frees the document's heap memory while the C iterator remains active. This can lead to use-after-free conditions. The vulnerability has been fixed in versions 3.17.2 and 3.17.3.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
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)
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-416

Technical details

References

Community reviews

Related threats