Mozilla Firefox up to 153.3/156 XUL sandbox

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.0$5k-$25k0.70

Summaryinfo

A vulnerability categorized as critical has been discovered in Mozilla Firefox up to 153.3/156. Affected by this vulnerability is an unknown functionality of the component XUL. Such manipulation leads to sandbox. This vulnerability is documented as CVE-2026-100787. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 153.3/156. Affected by this issue is an unknown functionality of the component XUL. The manipulation with an unknown input leads to a sandbox vulnerability. Using CWE to declare the problem leads to CWE-265. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Sandbox escape in the XUL component. This vulnerability was fixed in Firefox ESR 153.4 and Firefox 157.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability is handled as CVE-2026-100787 since 09/26/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/29/2026). The MITRE ATT&CK project declares the attack technique as T1611.

Upgrading to version 153.4 or 157 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Sandbox
CWE: CWE-265 / CWE-264
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 153.4/157

Timelineinfo

09/26/2026 CVE reserved
09/29/2026 +3 days Advisory disclosed
09/29/2026 +0 days VulDB entry created
09/29/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-100787 (🔒)
GCVE (CVE): GCVE-0-2026-100787
GCVE (VulDB): GCVE-100-411356

Entryinfo

Created: 09/29/2026 15:26
Changes: 09/29/2026 15:26 (57)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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