CVE-2026-16554

Red Hat statement

This flaw is an integer overflow in the print_string_ptr() function of the cJSON library. A 32-bit size_t counter used to track escape characters can wrap around when a JSON string contains approximately 858,993,460 or more control characters, causing an undersized heap buffer to be allocated and subsequently overflowed when the JSON is printed. This issue does not affect the versions of cJSON, or of components that vendor/bundle it (such as rpm-ostree), as shipped with Red Hat Enterprise Linux, Red Hat Satellite, or OpenShift Container Platform. None of these products build or run cJSON, or components embedding it, as 32-bit (i686) binaries: Red Hat Enterprise Linux 7 and later do not support direct installation on or execution as a 32-bit x86 process, the RHEL 8/9 multilib compatibility layer does not include general application libraries such as cJSON, and RHEL 10 removed multilib support entirely. Since the underlying size_t overflow this flaw depends on only manifests on a 32-bit build, the vulnerable condition is not reachable on any architecture these products ship or run on. Additionally, the CVE Numbering Authority (CERT.PL) was unable to reach the cJSON project maintainer during disclosure, and this issue has only been confirmed in cJSON version 1.7.19; no official upstream fix is currently available.

Red Hat mitigation

No mitigation is required for Red Hat Enterprise Linux, Red Hat Satellite, or OpenShift Container Platform, as these products are not affected due to their exclusively 64-bit architecture support. No upstream fix is currently available for other affected configurations (for example, cJSON as built for 32-bit architectures in Fedora). As a general precaution, applications using cJSON on a 32-bit platform should avoid processing untrusted JSON input containing very large numbers of control characters within a single string value.