# CVE-2026-33948: jq: Embedded-NUL Truncation in CLI JSON Input Path Causes Prefix-Only Validation of Malformed Input

> jq truncates input at NUL bytes, allowing attackers to bypass validation and inject malicious data into downstream systems.

- **Severity:** Low 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Apr 2026
- **Updated:** 14 Apr 2026
- **Also known as:** ALPINE-CVE-2026-33948, AZL-82928, BELL-CVE-2026-33948, DEBIAN-CVE-2026-33948, ECHO-efe2-3845-7825, GHSA-32cx-cvvh-2wj9, SUSE-SU-2026:2283-1

## What is CVE-2026-33948?

CVE-2026-33948 is a low-severity vulnerability in jqlang jq, published on 13 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-20 (Improper Input Validation), CWE-170 (Improper Null Termination)

## Which versions are affected by CVE-2026-33948?

It affects 1 product.


Products: Jqlang Jq.

## How do I fix CVE-2026-33948?

Apply the vendor's patch.

## Is CVE-2026-33948 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33948 exists.

## Other vulnerabilities in jqlang jq

- [CVE-2026-32316](https://insights.sbomify.com/CVE-2026-32316/): jq: Integer overflow in jvp_string_append() allows Heap-based Buffer Overflow (high 8.2)
- [CVE-2024-53427](https://insights.sbomify.com/CVE-2024-53427/): Memory corruption in jq (high 8.1)
- [CVE-2025-48060](https://insights.sbomify.com/CVE-2025-48060/): AddressSanitizer: stack-buffer-overflow in jq_fuzz_execute (jv_string_vfmt) (high 7.7)
- [CVE-2023-49355](https://insights.sbomify.com/CVE-2023-49355/): Memory corruption in n/a (high 7.5)
- [CVE-2026-49839](https://insights.sbomify.com/CVE-2026-49839/): jq --rawfile invalid-state reuse after String too long causes heap-buffer-overflow (high 7.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33948 and fix it if it is affected.

What it is: CVE-2026-33948 is a low-severity vulnerability in jqlang jq, published on 13 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33948 exists.

Affected product: jqlang jq. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33948/ (Markdown: https://insights.sbomify.com/CVE-2026-33948/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33948
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33948
- OSV: https://osv.dev/vulnerability/CVE-2026-33948

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33948/
Summaries are generated and may contain mistakes; the official description above is the record.