---
id: "CVE-2026-120987"
kind: "vulnerability"
aliases: ["CVE-2026-120987"]
title: "Whale Browser: iframe sandbox can be bypassed in dual-tab setups"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["browser", "other", "whale-browser"]
not_affected_if: ["version-5.39.412.57-or-later"]
published_at: "2026-11-03T07:18:21+00:00"
first_seen_at: "2026-11-03T07:49:22+00:00"
updated_at: "2026-11-03T07:50:22+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120987", "first_seen_at": "2026-11-03T07:49:22+00:00"}]
---

# Whale Browser: iframe sandbox can be bypassed in dual-tab setups

Whale Browser versions before 5.39.412.57 let an attacker bypass the iframe sandbox when two tabs are open. A successful bypass lets a malicious page escape the restrictions meant to isolate embedded content.

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

## How to check

- Check the installed Whale Browser version in the browser's About page (version string not given in sources)

## Fix

- Whale Browser: move to `5.39.412.57` or later

## Timeline

- 2026-11-03T07:49:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120987

## From the sources

Whale Browser before 5.39.412.57 allows an attacker to bypass the iframe sandbox in a dual-tab environment.

---

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