vulnerability / NVI-00018413 / Revision 1
Oj: Stack Buffer Overflow in Oj::Doc#each_child via Deeply Nested Input
GitHub lists this reviewed advisory for oj. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
oj
source listed< 3.17.3
### Summary `Oj::Doc#each_child`, when invoked recursively over a deeply nested JSON document, overflows a fixed-size stack buffer and aborts the process. This is a denial of service reachable from untrusted JSON. ### Details Two-step chain in `ext/oj/fast.c`: 1. **`doc_each_child` (~line 1501)** increments `doc->where` past the `where_path[MAX_STACK = 100]` array with no bounds check, and never restores it (`doc->where--` is missing). Calling `each_child` recursively from inside the yield block therefore drives `doc->where` beyond the array. 2. **On the next entry (~line 1478)** the function copies the path into a stack-local buffer: ```c Leaf save_path[MAX_STACK]; // 800-byte stack buffer size_t wlen = doc->where - doc->where_path; if (0 where_path, sizeof(Leaf) * (wlen + 1)); } ``` When the previous recursive call left `doc->where` past `where_path[100]`, `wlen` exceeds `MAX_STACK` and the `memcpy` overflows `save_path` on the C stack. The `Oj::Doc` parser imposes no JSON nesting-depth limit (it relies on a C-stack pressure check), so deeply nested attacker input reaches this path.
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-3m6q-jj5j-38c9 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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