CVE-2026-43894 jq: Wild stack write via signed-integer overflow in decNumber D2U() macro
A signed-integer overflow in jq's decNumber library allows attackers to trigger a wild stack write, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43894?
CVE-2026-43894 is a medium-severity vulnerability in jqlang jq, published on 11 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
jq is a command-line JSON processor. In 1.8.1 and earlier, when decNumberFromString is given a number literal of INT_MAX-1 (2147483646) digits, the D2U() macro overflows during signed-int arithmetic. The wrapped negative value bypasses the heap-allocation size check, causes the function to use a 30-byte stack buffer, and then writes ≈715 million 16-bit units (≈1.4 GiB) at an offset 1.43 GiB below the stack frame. The written content is fully attacker-controlled (the parsed decimal digits, packed 3-per-unit).
Weakness: CWE-190
Which versions are affected by CVE-2026-43894?
It affects 1 product.
Products include Jqlang Jq.
How do I fix CVE-2026-43894?
Upgrade to a fixed version.
Is CVE-2026-43894 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43894 exists.
Other vulnerabilities in jqlang jq
- CVE-2026-32316 jq: Integer overflow in jvp_string_append() allows Heap-based Buffer Overflow
- CVE-2024-53427 Memory corruption in jq
- CVE-2025-48060 AddressSanitizer: stack-buffer-overflow in jq_fuzz_execute (jv_string_vfmt)
- CVE-2023-49355 Memory corruption in n/a
- CVE-2026-49839 jq --rawfile invalid-state reuse after String too long causes heap-buffer-overflow
Sources
Also known as ALPINE-CVE-2026-43894, AZL-86372, BELL-CVE-2026-43894, DEBIAN-CVE-2026-43894, ECHO-be81-926b-05ab, GHSA-5v7p-2r57-2g4g and 1 more.