jq: Missing runtime type checks for _strindices lead to crash and limited memory disclosure (CVE-2026-39956) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-39956

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

Answer in brief

CVE-2026-39956 records a Unknown severity vulnerability in jq: Missing runtime type checks for _strindices lead to crash and limited memory disclosure. The current sources do not mark it as known exploited. The current feed maps jqlang/jq (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Apr 13, 2026Updated Sep 4, 2026Source checked Sep 4, 2026First seen by HOL Sep 4, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps jqlang/jq (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
jqlang/jqgeneric	< 1.8.2	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for jqlang/jq.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Apr 13, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 4, 2026

Sources and claim methodology

Upstream source description

jq is a command-line JSON processor. Prior to version 1.8.2, 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, which is part of version 1.8.2.

Quoted source text, attributed separately from HOL analysis.