Answer in brief
CVE-2026-54896 records a High severity (CVSS 2.1) vulnerability in Oj: Heap Buffer Overflow in Oj.dump Exception Serialization via Large Indent. The current sources do not mark it as known exploited. The current feed maps oj (rubygems), oj (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 2.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps oj (rubygems), oj (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| ojrubygems | <3.17.2 | 3.17.3 |
| ojrubygems | >=0 <3.17.3 | 3.17.3 |
Published upstream
Jun 19, 2026
Evidence: source:nvd:source_dates:source-dates:recordSource modified
Oct 25, 2026
Evidence: source:nvd:source_dates:source-dates:recordFirst seen by HOL
Jun 19, 2026
### Summary `Oj.dump` in object mode 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. ### Version - **Software**: oj gem - **Affected**: all versions with `ext/oj/dump.h` - **Latest tested**: 3.17.1 (confirmed present) ### Details `ext/oj/dump.h`, line 75–77: ```c static void fill_indent(Out out, int depth) { if (0 < out->opts->indent) { memset(out->buf + out->cur, ' ', (size_t)(out->opts->indent * depth)); ``` When dumping an Exception object in `:object` mode, `dump_obj_attrs` calls `fill_indent` repeatedly for each attribute. The buffer is pre-allocated based on the serialized content but not the indentation overhead. With `indent: 5000` the indent block for a nested object exceeds the remaining buffer space, producing a heap-buffer-overflow of size 5,000 at the end of the allocated region. ASAN report: ``` ==101656==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x527000022c5e WRITE of size 5000 at 0x527000022c5e thread T0 #0 memset #1 fill_indent /ext/oj/dump.h:77 #2 dump_obj_attrs /ext/oj/dump_object.c:552 #3 dump_obj /ext/oj/dump_object.c:80 #4 oj_dump_obj_val /ext/oj/dump_object.c:708 #5 oj_dump_obj_to_json_using_params /ext/oj/dump.c:817 #6 dump_body /ext/oj/oj.c:1429 #7 dump /ext/oj/oj.c:1480 0x527000022c5e is located 0 bytes after 13150-byte region [0x52700001f900, 0x527000022c5e) ``` ### Reproduce ```ruby require "oj" obj = Oj.load('{"^o":"RuntimeError"}', mode: :object) Oj.dump(obj, mode: :object, indent: 5000) ``` ### Workarounds This is at the discretion of the developer and not a public facing option so the workaround is the develop should not use extreme indents and should not offer the option for users to dump Ruby data with unlimited indentation size.
Quoted source text, attributed separately from HOL analysis.