CVE-2026-41256: CWE-158: Improper Neutralization of Null Byte or NUL Character in jqlang jq
jq is a command-line JSON processor. In 1.8.1 and earlier, Top-level jq programs loaded from a file with -f are truncated at the first embedded NUL byte on current upstream HEAD. A crafted filter file such as . followed by \x00 and arbitrary suffix compiles and executes as only the prefix before the NUL. This leaves jq with a post-CVE-2026-33948 prefix/full-buffer mismatch on the compilation path even though the JSON parser path has already been fixed.
AI Analysis
Technical Summary
CVE-2026-41256 affects jq, a command-line JSON processor, in versions 1.8.1 and earlier. When loading top-level jq programs from a file using the -f option, the program is truncated at the first embedded NUL byte (\x00). A crafted filter file containing a prefix followed by a NUL byte and arbitrary suffix will compile and execute only the prefix portion. This results in a prefix/full-buffer mismatch on the compilation path, even though a previous vulnerability (CVE-2026-33948) related to the JSON parser was fixed. The vulnerability is classified as CWE-158 (Improper Neutralization of Null Byte or NUL Character).
Potential Impact
The vulnerability allows an attacker to craft a filter file that truncates execution at the NUL byte, potentially causing unexpected behavior or logic errors in jq processing. The CVSS score is 5.5 (medium severity), indicating limited impact with no confidentiality or availability impact but with high integrity impact. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch is currently documented. Users should avoid processing untrusted jq filter files containing embedded NUL bytes until a fix is available.
CVE-2026-41256: CWE-158: Improper Neutralization of Null Byte or NUL Character in jqlang jq
Description
jq is a command-line JSON processor. In 1.8.1 and earlier, Top-level jq programs loaded from a file with -f are truncated at the first embedded NUL byte on current upstream HEAD. A crafted filter file such as . followed by \x00 and arbitrary suffix compiles and executes as only the prefix before the NUL. This leaves jq with a post-CVE-2026-33948 prefix/full-buffer mismatch on the compilation path even though the JSON parser path has already been fixed.
CVSS v3.1
Score 5.5medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-41256 affects jq, a command-line JSON processor, in versions 1.8.1 and earlier. When loading top-level jq programs from a file using the -f option, the program is truncated at the first embedded NUL byte (\x00). A crafted filter file containing a prefix followed by a NUL byte and arbitrary suffix will compile and execute only the prefix portion. This results in a prefix/full-buffer mismatch on the compilation path, even though a previous vulnerability (CVE-2026-33948) related to the JSON parser was fixed. The vulnerability is classified as CWE-158 (Improper Neutralization of Null Byte or NUL Character).
Potential Impact
The vulnerability allows an attacker to craft a filter file that truncates execution at the NUL byte, potentially causing unexpected behavior or logic errors in jq processing. The CVSS score is 5.5 (medium severity), indicating limited impact with no confidentiality or availability impact but with high integrity impact. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch is currently documented. Users should avoid processing untrusted jq filter files containing embedded NUL bytes until a fix is available.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-18T14:01:46.801Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a021aa3cbff5d861043037f
Added to database: 05/11/2026, 18:06:27 UTC
Last enriched: 06/24/2026, 15:10:50 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 97
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