Mozilla announced this week the release of Firefox 111, which patches over a dozen vulnerabilities, including potentially serious issues.
Of the 13 CVEs, seven have been assigned a ‘high’ severity rating. Three of them only impact Firefox for Android, and they can allow a hacker to hide fullscreen notifications — this can lead to user confusion or spoofing attacks — and open third-party apps without a prompt.
Other high-severity flaws patched with the latest Firefox updates can lead to arbitrary code execution and information disclosure.
Cybersecurity firm Sophos has analyzed the patches and highlighted two vulnerabilities: CVE-2023-28161 and CVE-2023-28163. Sophos said in a blog post:
- CVE-2023-28161: One-time permissions granted to a local file were extended to other local files loaded in the same tab. With this bug, if you opened a local file (such as downloaded HTML content) that wanted access, say, to your webcam, then any other local file you opened afterwards would magically inherit that access permission without asking you. As Mozilla noted, this could lead to trouble if you were looking through a collection of items in your download directory – the access permission warnings you’d see would depend on the order in which you opened the files.
- CVE-2023-28163: Windows Save As dialog resolved environment variables. This is another keen reminder to sanitise thine inputs, as we like to say. In Windows commands, some character sequences are treated specially, such as %USERNAME%, which gets converted to the name of the currently logged-on user, or %PUBLIC%, which denotes a shared directory, usually in C:\Users. A sneaky website could use this as a way to trick you into seeing and approving the download of a filename that looks harmless but lands in a directory you wouldn’t expect (and where you might not later realise it had ended up).
Cybersecurity agencies in Canada and the US have informed users about the latest Firefox patches, urging them to read the advisories and apply the necessary updates.
Firefox vulnerabilities are not as targeted by threat actors as flaws affecting Chrome, but users should not ignore the potential risks. CISA’s known exploited vulnerabilities catalog lists 10 Firefox vulnerabilities discovered over the past decade.
In addition, Mozilla announced this week that it’s looking into making the Firefox Relay email and phone number masking tool available directly within Firefox.
Related: Emergency Firefox Update Patches Two Actively Exploited Zero-Day Vulnerabilities
Related: Firefox Updates Patch 10 High-Severity Vulnerabilities

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.
More from Eduard Kovacs
- Exploitation of 55 Zero-Day Vulnerabilities Came to Light in 2022: Mandiant
- Organizations Notified of Remotely Exploitable Vulnerabilities in Aveva HMI, SCADA Products
- Waterfall Security, TXOne Networks Launch New OT Security Appliances
- Hitachi Energy Blames Data Breach on Zero-Day as Ransomware Gang Threatens Firm
- New York Man Arrested for Running BreachForums Cybercrime Website
- Exploitation of Recent Fortinet Zero-Day Linked to Chinese Cyberspies
- Mozilla Patches High-Severity Vulnerabilities With Release of Firefox 111
- Microsoft: 17 European Nations Targeted by Russia in 2023 as Espionage Ramping Up
Latest News
- Verosint Launches Account Fraud Detection and Prevention Platform
- Ransomware Gang Publishes Data Allegedly Stolen From Maritime Firm Royal Dirkzwager
- Zoom Paid Out $3.9 Million in Bug Bounties in 2022
- Oleria Scores $8M Seed Funding for ID Authentication Technology
- Exploitation of 55 Zero-Day Vulnerabilities Came to Light in 2022: Mandiant
- News Analysis: UK Commits $3 Billion to Support National Quantum Strategy
- Malicious NuGet Packages Used to Target .NET Developers
- Google Pixel Vulnerability Allows Recovery of Cropped Screenshots
