CVE-2026-8091 critical CVSS 9.8

Vulnerability in firefox (CVE-2026-8091)

Summary

vulnerability in firefox (CVE-2026-8091). Successful exploitation can lead to full system takeover.

Original description

The description as published by the source.

Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox ESR 140.10.2 and Firefox ESR 115.35.2.

Source: NIST National Vulnerability Database NVD GitHub Advisory

AI summary

Written by an external AI model and may contain mistakes. Check the original description and references below before acting on it.

A critical security issue was discovered in Firefox's audio/video playback, allowing attackers to remotely access and compromise private information. Past issues like Heartbleed and Log4Shell have shown similar dangers. Companies should urgently apply the latest security updates to mitigate potential risks.

Incorrect boundary conditions in the audio/video playback component allow remote attacks. The affected versions are unspecified, but it's fixed in Firefox ESR 140.10.2 and 115.35.2. Applying this patch is the only mitigation. Attackers can access without authentication and require no user interaction. Trace detection can be implemented by monitoring abnormal network traffic in a SIEM system.

❓ What is the problem

Incorrect boundary conditions in the Audio/Video: Playback component.

📍 Affected scope

Audio/Video: Playback component in Firefox.

🔥 Severity

Critical severity with remote network attack possible without user interaction or authentication.

🔧 How to fix

Update to Firefox ESR 140.10.2 or Firefox ESR 115.35.2.

🛡️ Workaround

No workaround available.

🔍 Detection

Monitor abnormal network traffic using SIEM tools for signs of exploitation.

Related past incidents Similar incidents extracted from past CVEs

Heartbleed

Similar boundary condition issue that allowed data exposure from memory.

Log4Shell

Remote code execution vulnerability via logging mechanism.

If this happens at your company Expected impact per business scenario

📌 E-commerce website using Firefox.

User data exposure leading to loss of customer trust.

📌 Corporate systems using Firefox for internal browsing.

Possible data leaks of sensitive corporate information.

📌 Service providers relying on secure communication via browsers.

Interruption in services due to compromised browser security.

Recommended action

Immediate application of the security patches to affected systems running Firefox.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
依存マニフェストで影響コンポーネントを特定する。
7
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 3 と同じログクエリでアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Debian DEBIAN-CVE-2026-8091 firefox-esr Fixed in: 140.10.1esr-1~deb11u1
Ubuntu UBUNTU-CVE-2026-8091 mozjs52