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CVE-2026-43894

MEDIUMCVSS 5.5/10EPSS 0.16%

Last modified

CVE-2026-43894 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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. EPSS estimates a 0.16% chance of exploitation in the next 30 days.

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).

Metrics

CVSS 3.1
5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
0.16%

5.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
JqlangJq<= 1.8.1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-43894?
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).
How severe is CVE-2026-43894?
CVE-2026-43894 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.16% probability of exploitation in the next 30 days.
How do I fix CVE-2026-43894?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-43894?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST