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Fencer Vulns
medium 5.3

CVE-2026-33948 json

jq: Embedded-NUL Truncation in CLI JSON Input Path Causes Prefix-Only Validation of Malformed Input

published 2026-04-13 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-22158

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits
0
none known

Summary

jq is a command-line JSON processor. Commits before 6374ae0bcdfe33a18eb0ae6db28493b1f34a0a5b contain a vulnerability where CLI input parsing allows validation bypass via embedded NUL bytes. When reading JSON from files or stdin, jq uses strlen() to determine buffer length instead of the actual byte count from fgets(), causing it to truncate input at the first NUL byte and parse only the preceding prefix. This enables an attacker to craft input with a benign JSON prefix before a NUL byte followed by malicious trailing data, where jq validates only the prefix as valid JSON while silently discarding the suffix. Workflows relying on jq to validate untrusted JSON before forwarding it to downstream consumers are susceptible to parser differential attacks, as those consumers may process the full input including the malicious trailing bytes. This issue has been patched by commit 6374ae0bcdfe33a18eb0ae6db28493b1f34a0a5b.

Patch / fix

  • jq Debian 12 1.6-2.1+deb12u2
  • jq Debian 13 1.7.1-6+deb13u2
  • jq Debian 14 1.8.1-5

debian advisories DEBIAN-CVE-2026-33948

  • jq Ubuntu 22.04 LTS 1.6-2.1ubuntu3.2
  • jq Ubuntu 24.04 LTS 1.7.1-3ubuntu0.24.04.2
  • jq Ubuntu 25.10 1.8.1-3ubuntu1.1
  • jq Ubuntu 26.04 LTS 1.8.1-4ubuntu2
  • jq Ubuntu Pro 16.04 LTS 1.5+dfsg-1ubuntu0.1+esm4
  • jq Ubuntu Pro 18.04 LTS 1.5+dfsg-2ubuntu0.1~esm2
  • jq Ubuntu Pro 20.04 LTS 1.6-1ubuntu0.20.04.1+esm2

ubuntu advisories UBUNTU-CVE-2026-33948

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jq hummingbird 1 1.8.1-3.hum1

red hat advisories RHSA-2026:8579

  • jq SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +11 more 1.7.1-150000.3.25.1
  • jq Linux Micro 6.0 1.7.1-1.1
  • jq Linux Micro 6.0 1.6-6.1
  • jq SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 1.7.1-160000.3.1
  • jq Linux Micro 6.1 1.7.1-slfo.1.1_3.1

suse advisories SUSE-SU-2026:4275-1SUSE-SU-2026:23873-1SUSE-SU-2026:22705-1SUSE-SU-2026:22545-1SUSE-SU-2026:22566-1SUSE-SU-2026:22664-1

  • jq openSUSE Leap 16.0 1.7.1-160000.3.1
  • jq openSUSE Tumbleweed 1.8.1-3.1

opensuse advisories openSUSE-SU-2026:21248-1openSUSE-SU-2026:10850-1

  • jq Alpine 3.24, Alpine 3.23, Alpine 3.22 1.8.2-r0

alpine advisories ALPINE-CVE-2026-33948

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jq Azure Linux 3.0 1.7.1-5

azure linux advisories AZL-82928

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33948 updated cvss 3.8

jq: jq: Input validation bypass via embedded NUL bytes allows parser differential attacks

  • Red Hat Enterprise Linux 8 jq Red Hat Enterprise Linux 9 jq Red Hat Enterprise Linux 10 jq Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images jq 1.8.1-3.hum1
    fixed: vendor fix RHSA-2026:8579

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/jqlang/jq/security/advisories/GHSA-32cx-cvvh-2wj9 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 2.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
CNA 4.0 2.9 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

  • jqlang jq

Classification

Weakness
  • CWE-170 Improper Null Termination
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.