jq: Missing runtime type checks for _strindices lead to crash and limited memory disclosure

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Summary

CVECVE-2026-39956
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-13 23:16:27 UTC
Updated2026-04-13 23:16:27 UTC
Descriptionjq is a command-line JSON processor. In commits after 69785bf77f86e2ea1b4a20ca86775916889e91c9, the _strindices builtin in jq's src/builtin.c passes its arguments directly to jv_string_indexes() without verifying they are strings, and jv_string_indexes() in src/jv.c relies solely on assert() checks that are stripped in release builds compiled with -DNDEBUG. This allows an attacker to crash jq trivially with input like _strindices(0), and by crafting a numeric value whose IEEE-754 bit pattern maps to a chosen pointer, achieve a controlled pointer dereference and limited memory read/probe primitive. Any deployment that evaluates untrusted jq filters against a release build is vulnerable. This issue has been patched in commit fdf8ef0f0810e3d365cdd5160de43db46f57ed03.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

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

Problem Types: CWE-125 | CWE-476 | CWE-843 | CWE-125 CWE-125: Out-of-bounds Read | CWE-476 CWE-476: NULL Pointer Dereference | CWE-843 CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
3.1CNADECLARED6.1MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jqlang Jq affected >= 69785bf77f86e2ea1b4a20ca86775916889e91c9, < fdf8ef0f0810e3d365cdd5160de43db46f57ed03 Not specified

References

ReferenceSourceLinkTags
github.com/jqlang/jq/security/advisories/GHSA-6gc3-3g9p-xx28 [email protected] github.com
github.com/jqlang/jq/commit/fdf8ef0f0810e3d365cdd5160de43db46f57ed03 [email protected] github.com
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