CVE-2026-54902: medium-severity vulnerability in ohler55 oj
Oj: Use-After-Free in Oj::Parser SAJ Long Key Callback
Published · Updated
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.3epss 0.4%
exploitation probability
0.4%top 64% of all CVEs
observed exploitation
nono source reports it
Oj (Optimized JSON) is a JSON parser and Object marshaller packaged as a Ruby gem. Prior to version 3.17.2, is vulnerable to Use-After-Free when in SAJ mode. The Oj::Parser does not protect cached object keys (≥ 35 bytes) from garbage collection, and a Ruby callback that triggers GC inside hash_end can cause the key string to be reclaimed while the C parser still holds a pointer to it. The subsequent access to the freed string VALUE results in a segfault, confirmed by an RIP pointing to address 0x4242 (a canary-style pattern suggesting control over the freed memory's content). This issue has been fixed in version 3.17.2.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA: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-2026-54502MEDIUMOj: 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%CVE-2026-54592HIGHOj: Stack Buffer Overflow in Oj::Doc#each_child via Deeply Nested InputEPSS 0.3%