jq: Algorithmic complexity DoS via hardcoded MurmurHash3 seed_CVE-2026-40164

7.5 / 10

HIGH

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

Description

jq is a command-line JSON processor. Before commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784, jq used MurmurHash3 with a hardcoded, publicly visible seed (0x432A9843) for all JSON object hash table operations, which allowed an attacker to precompute key collisions offline. By supplying a crafted JSON object (~100 KB) where all keys hashed to the same bucket, hash table lookups degraded from O(1) to O(n), turning any jq expression into an O(n²) operation and causing significant CPU exhaustion. This affected common jq use cases such as CI/CD pipelines, web services, and data processing scripts, and was far more practical to exploit than existing heap overflow issues since it required only a small payload. This issue has been patched in commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784.

Basic Information

ID CVE-2026-40164

Source GitHub_M

Published Apr 13, 2026 at 23:40

Affected Product

Vendor jqlang

Product jq

Version < 0c7d133c3c7e37c00b6d46b658a02244fdd3c784

Affected Versions jqlang jq < 0c7d133c3c7e37c00b6d46b658a02244fdd3c784

CWE Classification

CWE-328 CWE-407

References

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    "published": "2026-04-13T23:40:12.693Z",
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