CVE-2026-54500: medium-severity vulnerability in ohler55 oj
Oj: intern.c form_attr has an uninitialized stack read
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.2%
exploitation probability
0.2%top 91% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected products
ohler55 · ojRelated CVEs — ohler55 oj
In the same product, most dangerous first.
CVE-2026-54900MEDIUMOj: Negative-Size memcpy in Oj::Parser create_id Attribute HandlingEPSS 0.4%CVE-2026-54902MEDIUMOj: Use-After-Free in Oj::Parser SAJ Long Key CallbackEPSS 0.4%CVE-2026-54502MEDIUMOj: Stack Buffer Overflow in Oj.dump via Large IndentEPSS 0.3%CVE-2026-54903MEDIUMOj: Integer Overflow in Oj.load 2GB String HandlingEPSS 0.3%CVE-2026-54901MEDIUMOj: Use-After-Free in Oj::Parser array_class/hash_class GC MarkingEPSS 0.3%CVE-2026-54899MEDIUMOj: Use-After-Free in Oj::Parser Symbol Key Cache ToggleEPSS 0.3%