CVE-2026-6765
Mozilla Firefox ≤ 140.10.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NSummary
CVE-2026-6765 is a medium-severity Exposure of Private Personal Information to an Unauthorized Actor (CWE-359) vulnerability in Mozilla Firefox. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data from Local System (T1005); ranked at the 12th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-21 (Information Sharing) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-6765 is an information disclosure vulnerability in the Form Autofill component of Mozilla products. It affects Firefox versions prior to 150, Firefox ESR versions prior to 140.10, Thunderbird versions prior to 150, and Thunderbird versions prior to 140.10. The issue, classified under CWE-359 (Exposure of Private Information to an Unauthorized Actor), carries a CVSS v3.1 base score of 5.3, reflecting medium severity with network accessibility, low attack complexity, no privileges or user interaction required, unchanged scope, and low confidentiality impact.
Unauthenticated remote attackers can exploit this vulnerability over the network without user interaction. Successful exploitation allows disclosure of sensitive information stored or handled by the Form Autofill feature, such as autofill data, though the impact is limited to low confidentiality without affecting integrity or availability.
Mozilla Security Advisories (MFSA 2026-30, 32, 33, and 34) and the associated Bugzilla entry detail the fix applied in the specified versions. Mitigation requires updating to Firefox 150, Firefox ESR 140.10, Thunderbird 150, or Thunderbird 140.10, as no additional workarounds are mentioned.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24106
Vulnerability Data
Information disclosure in the Form Autofill component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 2 hardening rules · 2 OS baselines
V10.3.5V10.7.2
Mitigating Controls (NIST 800-53 r5) AI
Enforces authorizations so that PII is not reachable by unauthorized actors.
Requires explicit verification that a recipient's authorizations match the sensitivity of shared PII.
Limits granted rights to the minimum needed, reducing the set of actors who can reach private data.
Documents the legal or consent basis required before any processing of PII occurs.
Implements consent mechanisms that directly block access absent the individual's permission.
Encrypts or otherwise protects stored PII against unauthorized retrieval.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
CWE-359 does not impair RC.CO-04's ability to issue approved public recovery updates, yet any resulting PII exposure can partially undermine the outcome's overall efficacy and trust.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Masking or anonymizing personal identifiers limits the amount of private personal information that can be disclosed through application outputs or logs.
Monitoring and quarantining outbound messages that contain personal or private data directly reduces the chance that such information will be disclosed to unauthorized recipients.
The explicit prohibition on copying personally identifiable information into development and test environments directly lowers the exposure of private personal data to staff or processes that should not see it.
Labeling, chain-of-custody, and access-control requirements limit the exposure of private personal information during any transfer method.
Mandating privacy procedures and a designated privacy officer helps ensure that private personal information is not disclosed without proper authorization or necessity.
The agreements impose enforceable restrictions on the handling of private personal information, thereby decreasing the risk that such data will be exposed to unauthorized parties.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Ubuntu 22.04 (1 rule)
- V-260531 Ubuntu 22.04 LTS must configure the SSH daemon to use FIPS 140-3-approved ciphers to prevent the unauthorized disclosure of information and/or detect changes to information during transmission. prevents CWE-359
Ubuntu 24.04 (1 rule)
- V-270670 Ubuntu 24.04 LTS must configure the SSH client to use FIPS 140-3 approved ciphers to prevent the unauthorized disclosure of information and/or detect changes to information during transmission. prevents CWE-359