Mozilla Firefox up to 140.10/150 HTTP cross-domain policy

CVSS Meta Temp Score
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CTI Interest Score
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7.6$5k-$25k0.80

Summaryinfo

A vulnerability labeled as critical has been found in Mozilla Firefox up to 140.10/150. The impacted element is an unknown function of the component HTTP Component. The manipulation results in cross-domain policy. This vulnerability was named CVE-2026-8950. The attack may be performed from remote. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 140.10/150. It has been classified as critical. Affected is an unknown part of the component HTTP Component. The manipulation with an unknown input leads to a cross-domain policy vulnerability. CWE is classifying the issue as CWE-942. The product uses a cross-domain policy file that includes domains that should not be trusted. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Same-origin policy bypass in the Networking: HTTP component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability is traded as CVE-2026-8950 since 05/19/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. 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 06/17/2026).

The vulnerability scanner Nessus provides a plugin with the ID 315532 (Linux Distros Unpatched Vulnerability : CVE-2026-8950), 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 (315532) and CERT Bund (WID-SEC-2026-1606). Once again VulDB remains the best source for 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: 7.8
VulDB Meta Temp Score: 7.6

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

ADP CISA Base Score: 9.3
ADP CISA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Cross-domain policy
CWE: CWE-942 / CWE-346 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 315532
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-8950

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-2026-8950 (🔒)
GCVE (CVE): GCVE-0-2026-8950
GCVE (VulDB): GCVE-100-364668
CERT Bund: WID-SEC-2026-1606 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 05/19/2026 15:55
Updated: 06/17/2026 19:34
Changes: 05/19/2026 15:55 (55), 05/20/2026 12:16 (2), 05/23/2026 12:24 (12), 06/17/2026 19:34 (7)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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