CVE-2026-116733
flatcc through 0.6.4 Out-of-Bounds Read via __flatcc_json_parser_number
flatcc through 0.6.4 contains an out-of-bounds read vulnerability in __flatcc_json_parser_number that allows attackers to read past the input buffer via numbers ending in a decimal point. Attackers can supply untrusted JSON ending immediately after a decimal point to generated parsers, crashing applications when the buffer ends at an unmapped page.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| flatcc dvidelabs dvidelabs/flatcc
github |
≥ 0; ≤ 0.6.4 (affected, custom)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.3 medium |
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 | CNA: VulnCheck |
| 3.1 / 3.7 low |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L | CNA: VulnCheck |
Exploit evidence
- https://hackmd.io/@haindpwn/cve-2026-116733-116734-flatcc-json-number-oob-read
exploit · ADP: CISA-ADP
References
- https://github.com/dvidelabs/flatcc/commit/356792dc155a9e685acdfe0ec1e209bdadcb4ab9CNA: VulnCheck · patch
- https://github.com/dvidelabs/flatccCNA: VulnCheck · product
- https://github.com/dvidelabs/flatcc/blob/v0.6.4/src/runtime/json_parser.c#L539-L543CNA: VulnCheck · technical-description
- https://hackmd.io/@haindpwn/flatcc-json-number-oob-readCNA: VulnCheck · third-party-advisory
- https://www.vulncheck.com/advisories/flatcc-through-0.6.4-out-of-bounds-read-via-flatcc-json-parser-numberCNA: VulnCheck · third-party-advisory
- https://hackmd.io/@haindpwn/cve-2026-116733-116734-flatcc-json-number-oob-readADP: CISA-ADP · exploit
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