PT-2026-51084 · Rubygems · Oj

Published 2026-06-19 · Updated 2026-06-19 · CVE-2026-54898

Positive Technologies (AI Summary)

CVSS v4.0

8.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Name of the Vulnerable Software and Affected Versions oj gem (affected versions not specified)

Description A heap use-after-free occurs in Oj::Parser#parse when a SAJ/SAJ2 callback mutates the input JSON string during the parsing process. The C engine maintains a raw pointer to the Ruby string's internal buffer. If a callback, such as hash start(), resizes the string (for example, via String#replace), Ruby reallocates the buffer and frees the original memory. This leaves the C parser with a dangling pointer, leading to a use-after-free when the next character is read.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Use After Free

Weakness Enumeration

CWE-416

Related Identifiers

CVE-2026-54898

GHSA-Q2GM-54R6-8FWM

Affected Products

Oj

References · 3

• https://osv.dev/vulnerability/GHSA-q2gm-54r6-8fwm · Vendor Advisory
• https://github.com/ohler55/oj · Note
• https://github.com/ohler55/oj/security/advisories/GHSA-q2gm-54r6-8fwm · Note