---
id: "CVE-2026-120458"
kind: "vulnerability"
aliases: ["CVE-2026-120458"]
title: "Kvazaar: truncated Y4M header makes the encoder hang forever"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["command-line", "kvazaar", "package", "video-encoding"]
not_affected_if: ["no-kvazaar-installed", "trusted-input-only"]
published_at: "2026-11-02T15:17:29+00:00"
first_seen_at: "2026-11-02T15:24:03+00:00"
updated_at: "2026-11-02T15:26:14+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120458", "first_seen_at": "2026-11-02T15:24:03+00:00"}]
---

# Kvazaar: truncated Y4M header makes the encoder hang forever

Kvazaar, a video encoder, loops forever when its command-line tool reads a Y4M file whose header lacks a terminating newline. An attacker who supplies such a file can keep the process busy at full CPU, a denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Kvazaar version (`kvazaar --version`) and compare it with the versions the sources list as affected (through 2.3.2).
- Look for places where the command-line encoder is run on untrusted .y4m files, such as upload or transcoding pipelines.

## Fix

- Kvazaar: unknown; the sources link a patch and release notes but do not state the fixed version in the text provided.

## Timeline

- 2026-11-02T15:24:03+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120458

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/kvazaar-through-2.3.2-infinite-loop-dos-via-y4m-header-parser
- [fix] Patch: github.com https://github.com/ultravideo/kvazaar/commit/8a2f109be283e87008c679d635966cc034da39c6
- [fix] Release notes: github.com https://github.com/ultravideo/kvazaar/releases/tag/v2.3.2

## From the sources

Kvazaar through 2.3.2 contains an infinite loop vulnerability in read_header() in src/encmain.c that allows attackers to hang the command-line encoder by supplying a truncated Y4M header. Attackers can provide a crafted .y4m file lacking a terminating newline, causing unchecked EOF reads that hang the process indefinitely while consuming a full CPU core.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_