CVE-2026-6779
Published: 21 April 2026
Description
Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Directly implements checks on information inputs to reject invalid data before processing.
Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.
Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.
Managed runtimes used by platform-independent applications (e.g., JVM, CLR) enforce memory safety, preventing most buffer overflows that require direct memory manipulation.
Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.
Memory protections (e.g., W^X, ASLR) make exploitation of buffer-boundary violations far harder to turn into code execution.
Detects exploitation attempts that produce memory corruption, crashes, or anomalous behavior.
Security SummaryAI
CVE-2026-6779 is an unspecified issue in the JavaScript Engine component affecting Mozilla Firefox and Thunderbird. The vulnerability, associated with CWE-20 (Improper Input Validation), CWE-79 (Cross-site Scripting), and CWE-119 (Buffer Overflow), received a CVSS v3.1 base score of 5.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N), indicating medium severity with low confidentiality impact. It was publicly disclosed on 2026-04-21 and addressed in Firefox version 150 and Thunderbird version 150.
Unauthenticated attackers can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation allows limited disclosure of sensitive information without impacting integrity or availability, and the scope remains unchanged.
Mozilla's security advisories (MFSA 2026-30 and MFSA 2026-33) confirm the fix in Firefox 150 and Thunderbird 150, with additional details available in Bugzilla ticket 2023343. Security practitioners should ensure affected users upgrade to these patched versions to mitigate the risk.
Details
- CWE(s)
Affected Products
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
JS engine vuln with XSS/buffer overflow enables client app exploitation and JS interpreter abuse for info disclosure.