CVE-2026-40164
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk29th percentile - higher than 29% of all known CVEs
Summary
Before commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784, jq used MurmurHash3 with a hardcoded, publicly visible seed (0x432A9843) for all JSON object hash table operations, allowing an attacker to precompute key collisions offline. A crafted JSON object (~100 KB) with all keys hashing to the same bucket degrades lookups from O(1) to O(n), causing CPU exhaustion.
Risk Assessment
This attack is easy to exploit with a small payload and can cause significant CPU exhaustion, affecting CI/CD pipelines, web services, and data processing scripts, leading to denial of service.
Recommendation
Immediately update jq to a version containing commit 0c7d133c3c7e37c00b6d46b658a02244fdd3c784 or later to eliminate the collision vulnerability.
Other vulnerabilities in jq
See all- CVE-2016-4074High
The jv_dump_term function in jq 1.5 allows remote attackers to cause a denial of service via a crafted JSON file, leading to stack consumption and application crash. This issue has been fixed in jq 1.6_rc1-r0.
- CVE-2024-53427Medium
The decNumberCopy function in decNumber.c in jq through 1.7.1 does not properly consider that NaN is interpreted as numeric, which has a resultant stack-based buffer overflow and out-of-bounds write. This can be demonstrated by using --slurp with subtraction, such as a filter of .-. when the input has a certain form.
- CVE-2015-8863Critical
Off-by-one error in the tokenadd function in jv_parse.c in jq allows remote attackers to cause a denial of service (crash) via a long JSON-encoded number, which triggers a heap-based buffer overflow.
- CVE-2026-39979Medium
In the libjq library (part of the jq tool), the jv_parse_sized() function has an out-of-bounds read vulnerability. When processing malformed JSON in a non-NUL-terminated buffer, the error formatting function uses %s which reads until a NUL terminator, ignoring the caller-supplied length.
Original NVD description (English source)
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.