Bug 2458076 (CVE-2026-39956)

Summary: CVE-2026-39956 jq: missing runtime type checks for _strindices lead to crash and limited memory disclosure
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: amctagga, aoconnor, bniver, crizzo, dschmidt, erezende, flucifre, gmeno, groman, jlanda, jmitchel, kshier, mbenjamin, mhackett, rhel-process-autobot, simaishi, smcdonal, sostapov, stcannon, teagle, vereddy, watson-tool-maintainers, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in jq, a command line JSON processor. In release builds, the `_strindices` builtin function calls the `jv_string_indexes` function without checking that the arguments are actually strings. This missing validation allows an attacker who can supply non-string inputs to cause an application crash and a limited memory read.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2458402    
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Description OSIDB Bzimport 2026-04-13 23:01:20 UTC 
jq 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.