Vulnerability · Published Jun 30, 2026 · Assigned by GitHub_M
CVE-2026-54500Oj: intern.c form_attr has an uninitialized stack read
Medium 5.3
In plain English
A medium-severity out-of-bounds read in oj from ohler55. There are no confirmed reports of exploitation so far. 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 3.17.3, Oj.load in :object mode reads uninitialized stack memory (and, for long keys, reads out of bounds) when parsing a JSON object whose key is 254 bytes or longer. The interned bytes can surface to the caller, disclosing process stack memory. In ext/oj/intern.c, form_attr() handles the long-key path by allocating a heap buffer, `b`, populating it with the attribute name, and then freeing it — but it passed the uninitialized stack buffer buf (not b) to rb_intern3(). rb_intern3 therefore reads len + 1 bytes of uninitialized stack memory. When the key length is >= 256, it also reads out of bounds past the 256-byte buf. The resulting bytes are interned and can reach the caller via the produced Symbol or via the EncodingError message raised on invalid UTF-8, leaking process stack contents. This issue has been fixed in version 3.17.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | ruby-oj | 3.14.2-1+deb12u1 | DEBIAN-CVE-2026-54500 |
| Debian:13 | ruby-oj | 3.16.3-1+deb13u1 | DEBIAN-CVE-2026-54500 |
| Debian:14 | ruby-oj | 3.17.3-1 | DEBIAN-CVE-2026-54500 |
| RubyGems | oj | 3.17.3 | GHSA-fm7p-mprw-wjm9 |
| Ubuntu:22.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54500 |
| Ubuntu:24.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54500 |
| Ubuntu:25.10 | ruby-oj | no fix listed | UBUNTU-CVE-2026-54500 |
| Ubuntu:26.04:LTS | ruby-oj | no fix listed | UBUNTU-CVE-2026-54500 |
| Ubuntu:26.10 | ruby-oj | no fix listed | UBUNTU-CVE-2026-54500 |
Affected products (as reported)
Weakness: CWE-125, CWE-908 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- https://github.com/ohler55/oj/security/advisories/GHSA-fm7p-mprw-wjm9 x_refsource_CONFIRM