Cyber Resilience

CVE-2026-43894

Memory Safety in Jqlang Jq ≤ 1.8.1

Public PoCMemory Safety
Published
11 May 2026
Modified
17 June 2026
Patch / advisory
CVSS Score v3.1 6.2
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0016 5th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-43894 is a medium-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Jqlang Jq. Its CVSS base score is 6.2 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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…

more

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).

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
Why these techniques?

Stack buffer overflow from integer wrap in JSON number parser allows attacker-controlled data writes, directly enabling client-side code execution when a victim processes malicious input via jq.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-54679Same product: Jqlang Jq
CVE-2026-41257Same product: Jqlang Jq
CVE-2026-49839Same product: Jqlang Jq
CVE-2024-23337Same product: Jqlang Jq
CVE-2026-32316Same product: Jqlang Jq
CVE-2024-53427Same product: Jqlang Jq
CVE-2026-43896Same product: Jqlang Jq
CVE-2026-39956Same product: Jqlang Jq
CVE-2023-50268Same product: Jqlang Jq
CVE-2026-47770Same product: Jqlang Jq

Affected Assets

jqlang
jq
≤ 1.8.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • SI-10 Information Input Validation
  • SI-2 Flaw Remediation
  • SI-16 Memory Protection
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V5.2.6

Mitigating Controls (NIST 800-53 r5) AI

prevent

Rejects or bounds-checks the attacker-supplied decimal string before decNumberFromString performs the D2U arithmetic that overflows.

prevent

Requires prompt application of the vendor patch that corrects the signed-integer overflow and subsequent stack write in decNumberFromString.

prevent

Enforces memory protections that can block or contain the 1.4 GiB stack write that results from the bypassed size check.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

detects

Security testing in development can detect integer overflows before release.

prevents

Secure SDLC mandates input validation and arithmetic checks that prevent integer overflows.

degrades

Application security requirements include bounds checking and safe arithmetic to avoid overflow conditions.

degrades

Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.

prevents

Secure coding standards explicitly forbid unsafe integer operations and mandate overflow-safe constructs.

References