Mozilla Firefox up to 140.10/150 Workers privileges management

CVSS Meta Temp Score
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CTI Interest Score
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7.4$5k-$25k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 140.10/150. Affected by this issue is some unknown functionality of the component Workers. The manipulation leads to Remote Code Execution. This vulnerability is listed as CVE-2026-8955. The attack may be initiated remotely. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 140.10/150. This issue affects an unknown functionality of the component Workers. The manipulation with an unknown input leads to a remote code execution vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

The advisory is shared at bugzilla.mozilla.org. The identification of this vulnerability is CVE-2026-8955 since 05/19/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 06/17/2026). MITRE ATT&CK project uses the attack technique T1068 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 315529 (Linux Distros Unpatched Vulnerability : CVE-2026-8955), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 140.11 or 151 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (315529), EUVD (EUVD-2026-30905) and CERT Bund (WID-SEC-2026-1606). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • SUSE Linux
  • Oracle Linux
  • IGEL OS
  • SUSE openSUSE
  • RESF Rocky Linux
  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.6
VulDB Meta Temp Score: 7.4

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 8.8
ADP CISA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Privileges management
CWE: CWE-269 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
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Nessus ID: 315529
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-8955

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 140.11/151

Timelineinfo

05/19/2026 Advisory disclosed
05/19/2026 +0 days CVE reserved
05/19/2026 +0 days VulDB entry created
06/17/2026 +29 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-8955 (🔒)
GCVE (CVE): GCVE-0-2026-8955
GCVE (VulDB): GCVE-100-364673
EUVD: 🔒
CERT Bund: WID-SEC-2026-1606 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 05/19/2026 15:56
Updated: 06/17/2026 19:34
Changes: 05/19/2026 15:56 (54), 05/19/2026 17:30 (1), 05/20/2026 12:16 (2), 05/23/2026 12:24 (14), 06/17/2026 19:34 (7)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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