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CVE-2026-43894— jq: Wild stack write via signed-integer overflow in decNumber D2U() macro

Quick assessment

Affected
jqlang jq
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

jq是jqlang开源的一个轻量级且灵活的命令行 JSON 处理器。 jq 1.8.1及之前版本存在输入验证错误漏洞，该漏洞源于当decNumberFromString接收INT_MAX-1位数字文字时，D2U()宏在带符号整数算术期间溢出，包装的负值绕过堆分配大小检查，导致函数使用30字节栈缓冲区并写入约7.15亿个16位单元。

CVSS 6.2 · Medium EPSS 0.15% · P4

Affected Version Matrix 1

VendorProduct Version RangeStatus
jqlang jq <= 1.8.1 affected
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I. Basic Information for CVE-2026-43894

Vulnerability Information
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Vulnerability Title
jq: Wild stack write via signed-integer overflow in decNumber D2U() macro
Source: CVE Program / CVE List V5
Vulnerability 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).
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数溢出或超界折返
Source: CVE Program / CVE List V5
Vulnerability Title
jq 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
jq是jqlang开源的一个轻量级且灵活的命令行 JSON 处理器。 jq 1.8.1及之前版本存在输入验证错误漏洞，该漏洞源于当decNumberFromString接收INT_MAX-1位数字文字时，D2U()宏在带符号整数算术期间溢出，包装的负值绕过堆分配大小检查，导致函数使用30字节栈缓冲区并写入约7.15亿个16位单元。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
jqlang jq <= 1.8.1 -

II. Public POCs for CVE-2026-43894

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III. Intelligence Information for CVE-2026-43894

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Vendor Advisories for CVE-2026-43894 (1)

Same Patch Batch · jqlang · 2026-05-11 · 7 CVEs total

CVE-2026-43896 6.2 MEDIUM jq: Stack Overflow in Recursive Object Merge
CVE-2026-41256 5.5 MEDIUM jq: Embedded NUL truncates top-level jq programs loaded with -f
CVE-2026-43895 4.4 MEDIUM jq: Embedded NUL in jq import paths causes local redaction-policy bypass and preserves sen
CVE-2026-41257 jq: Signed-int overflow in `stack_reallocate` (jq VM stack)
CVE-2026-40612 jq: Stack overflow via unbounded recursion in jv_contains
CVE-2026-44777 jq: stack overflow in module loading on mutual `include`

IV. Related Vulnerabilities

Same product: jq
Same vendor: jqlang
Same weakness: CWE-190

V. Comments for CVE-2026-43894

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