CVE-2026-41256Public exploit

Integrity bypass via NUL-truncated filter compilation

Published May 11, 2026 · Updated May 11, 2026

Improper NUL-byte handling in jq 1.8.1 and earlier allows context-dependent attackers to bypass filter-file integrity checks via crafted -f input. The -f loader in src/main.c passes the counted file buffer to jq_compile_args, whose locfile_init call uses strlen and compiles only bytes before the first NUL. Exploitation requires a crafted filter file to be processed; jq silently ignores its suffix, undermining workflows that approve or sign the complete file.

CVSS severity5.5
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper NUL-byte handling in jq 1.8.1 and earlier allows context-dependent attackers to bypass filter-file integrity checks via crafted -f input. The -f loader in src/main.c passes the counted file buffer to jq_compile_args, whose locfile_init call uses strlen and compiles only bytes before the first NUL. Exploitation requires a crafted filter file to be processed; jq silently ignores its suffix, undermining workflows that approve or sign the complete file.

The record

CVE
CVE-2026-41256
Published
May 11, 2026
Updated
May 11, 2026
Vendor
jqlang
Product
jq
Classifications
CWE-158, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=<= 1.8.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

jqlang · jqversion=<= 1.8.1

Published CVSS scores

5.5jqlangCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

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-158Improper Neutralization of Null Byte or NUL Character
T1204.002User Execution: Malicious File

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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