Vulnerability · Published Jun 30, 2026 · Assigned by GitHub_M
CVE-2026-54896Oj: Heap Buffer Overflow in Oj.dump Exception Serialization via Large Indent
Low 2.1
In plain English
A low-severity heap buffer overflow in oj from ohler55. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. In versions prior to 3.17.2, when in object mode, Oj.dump is vulnerable to a heap buffer overflow when serializing Exception objects with a large :indent value. The serializer allocates a buffer sized for the object's attributes but does not account for the indent bytes added on each write. With indent: 5000, the accumulation of 5,000-byte indent strings overflows the 13,150-byte heap allocation, corrupting adjacent heap memory. This issue has been fixed in version 3.17.2.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ruby-oj | 3.14.2-1+deb12u1 | DEBIAN-CVE-2026-54896 |
| Debian:13 | ruby-oj | 3.16.3-1+deb13u1 | DEBIAN-CVE-2026-54896 |
| Debian:14 | ruby-oj | 3.17.3-1 | DEBIAN-CVE-2026-54896 |
| RubyGems | oj | 3.17.3 | GHSA-35w3-pjm6-wj95 |
| Ubuntu:22.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54896 |
| Ubuntu:24.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54896 |
| Ubuntu:25.10 | ruby-oj | no fix listed | UBUNTU-CVE-2026-54896 |
| Ubuntu:26.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54896 |
| Ubuntu:26.10 | ruby-oj | no fix listed | UBUNTU-CVE-2026-54896 |
Affected products (as reported)
Weakness: CWE-122 · 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
References
- https://github.com/ohler55/oj/security/advisories/GHSA-35w3-pjm6-wj95 x_refsource_CONFIRM