Opera before 57.0.3098.106 is vulnerable to a DLL Search Order hijacking attack where an attacker can send a ZIP archive composed of an HTML page along with a malicious DLL to the target. Once the document is opened, it may allow the attacker to take full control of the system from any location within the system. The issue lies in the loading of the shcore.dll and dcomp.dll files: these files are being searched for by the program in the same system-wide directory where the HTML file is executed.

The TLS protocol 1.2 and earlier supports the rsa_fixed_dh, dss_fixed_dh, rsa_fixed_ecdh, and ecdsa_fixed_ecdh values for ClientCertificateType but does not directly document the ability to compute the master secret in certain situations with a client secret key and server public key but not a server secret key, which makes it easier for man-in-the-middle attackers to spoof TLS servers by leveraging knowledge of the secret key for an arbitrary installed client X.509 certificate, aka the "Key Compromise Impersonation (KCI)" issue.

The HTTP/2 protocol does not consider the role of the TCP congestion window in providing information about content length, which makes it easier for remote attackers to obtain cleartext data by leveraging a web-browser configuration in which third-party cookies are sent, aka a "HEIST" attack.

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue.

Opera before 19 on Mac OS X allows user-assisted remote attackers to spoof the address bar via vectors involving a drag-and-drop operation.

The intent: URL implementation in Opera before 18 on Android allows attackers to read local files by leveraging an interaction error, as demonstrated by reading stored cookies.

Unspecified vulnerability in Opera before 12.15 has unknown impact and attack vectors, related to a "moderately severe issue."

Opera before 12.15 does not properly block top-level domains in Set-Cookie headers, which allows remote attackers to obtain sensitive information by leveraging control of a different web site in the same top-level domain.

The TLS implementation in Opera before 12.13 does not properly consider timing side-channel attacks on a MAC check operation during the processing of malformed CBC padding, which allows remote attackers to conduct distinguishing attacks and plaintext-recovery attacks via statistical analysis of timing data for crafted packets, a related issue to CVE-2013-0169.

Opera before 12.13 does not send CORS preflight requests in all required cases, which allows remote attackers to bypass a CSRF protection mechanism via a crafted web site that triggers a CORS request.

Opera before 12.13 allows remote attackers to execute arbitrary code via crafted clipPaths in an SVG document.

Opera before 12.13 allows remote attackers to execute arbitrary code via vectors involving DOM events.

Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 Update 10 and Update 11, when running on Windows using Internet Explorer, Firefox, Opera, and Google Chrome, allows remote attackers to bypass the "Very High" security level of the Java Control Panel and execute unsigned Java code without prompting the user via unknown vectors, aka "Issue 53" and the "Java Security Slider" vulnerability.

Opera before 12.12 on UNIX uses weak permissions for the profile directory, which allows local users to obtain sensitive information by reading a (1) cache file, (2) password file, or (3) configuration file, or (4) possibly gain privileges by modifying or overwriting a configuration file.

Opera before 12.12 allows remote attackers to spoof the address field via a high rate of HTTP requests.

Opera before 12.12 does not properly allocate memory for GIF images, which allows remote attackers to execute arbitrary code or cause a denial of service (memory overwrite) via a malformed image.

Opera before 12.11 allows remote attackers to determine the existence of arbitrary local files via vectors involving web script in an error page.

Heap-based buffer overflow in Opera before 12.11 allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a long HTTP response.

Opera before 11.67 and 12.x before 12.02 allows remote attackers to cause truncation of a dialog, and possibly trigger downloading and execution of arbitrary programs, via a crafted web site.

Opera before 12.01 allows remote attackers to cause a denial of service (application crash) via a crafted web site, as demonstrated by the Lenovo "Shop now" page.