CVE-2026-39956Public exploit

Process crash and memory probing via type confusion

Published Apr 13, 2026 · Updated Apr 13, 2026

Type confusion in jqlang jq 1.8.1 and earlier allows attackers to crash the process or probe limited memory via an untrusted filter. The _strindices wrapper passes non-string arguments to jv_string_indexes(), whose assert-only checks vanish in release builds, so numeric bits are treated as a string pointer. Exploitation requires a release build to evaluate an attacker-controlled jq filter; fixed queries that never invoke _strindices are unaffected.

CVSS severity6.1
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in jqlang jq 1.8.1 and earlier allows attackers to crash the process or probe limited memory via an untrusted filter. The _strindices wrapper passes non-string arguments to jv_string_indexes(), whose assert-only checks vanish in release builds, so numeric bits are treated as a string pointer. Exploitation requires a release build to evaluate an attacker-controlled jq filter; fixed queries that never invoke _strindices are unaffected.

The record

CVE
CVE-2026-39956
Published
Apr 13, 2026
Updated
Apr 13, 2026
Vendor
jqlang
Product
jq
Classifications
CWE-476, CWE-843, CWE-125, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 69785bf77f86e2ea1b4a20ca86775916889e91c9, < fdf8ef0f0810e3d365cdd5160de43db46f57ed03

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

jqlang · jqversion=>= 69785bf77f86e2ea1b4a20ca86775916889e91c9, < fdf8ef0f0810e3d365cdd5160de43db46f57ed03

Published CVSS scores

6.1GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
CWE-843Access of Resource Using Incompatible Type ('Type Confusion')
CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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