Opera : Security Vulnerabilities, CVEs, CVSS score between 5 and 5.99

Visual truncation vulnerability in Opera 9.21 allows remote attackers to spoof the address bar and possibly conduct phishing attacks via a long hostname, which is truncated after 34 characters, as demonstrated by a phishing attack using HTTP Basic Authentication.

Opera before 9.61 does not properly block scripts during preview of a news feed, which allows remote attackers to create arbitrary new feed subscriptions and read the contents of arbitrary feeds.

Opera cannot properly restrict modifications to cookies established in HTTPS sessions, which allows man-in-the-middle attackers to overwrite or delete arbitrary cookies via a Set-Cookie header in an HTTP response, related to lack of the HTTP Strict Transport Security (HSTS) includeSubDomains feature, aka a "cookie forcing" issue.

Google Chrome detects http content in https web pages only when the top-level frame uses https, which allows man-in-the-middle attackers to execute arbitrary web script, in an https site's context, by modifying an http page to include an https iframe that references a script file on an http site, related to "HTTP-Intended-but-HTTPS-Loadable (HPIHSL) pages."

Opera before 10.01 on Windows does not prevent use of Web fonts in rendering the product's own user interface, which allows remote attackers to spoof the address field via a crafted web site.

Opera before 10.10, when exception stacktraces are enabled, places scripting error messages from a web site into variables that can be read by a different web site, which allows remote attackers to obtain sensitive information or conduct cross-site scripting (XSS) attacks via unspecified vectors.

Opera before 9.63 does not properly verify X.509 certificates from SSL servers, which allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.

Opera for Android before 54.0.2669.49432 is vulnerable to a sandboxed cross-origin iframe bypass attack. By using a service working inside a sandboxed iframe it is possible to bypass the normal sandboxing attributes. This allows an attacker to make forced redirections without any user interaction from a third-party context.

The HTTPS 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 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.

Opera Mini for Android below 53.1 displays URL left-aligned in the address field. This allows a malicious attacker to craft a URL with a long domain name, e.g. www.safe.opera.com.attacker.com. With the URL being left-aligned, the user will only see the front part (e.g. www.safe.opera.com…) The exact amount depends on the phone screen size but the attacker can craft a number of different domains and target different phones. Starting with version 53.1 Opera Mini displays long URLs with the top-level domain label aligned to the right of the address field which mitigates the issue.

A design error in Opera 8.01 and earlier allows user-assisted attackers to execute arbitrary code by overlaying a malicious new window above a file download dialog box, then tricking the user into double-clicking on the "Run" button, aka "link hijacking".

Integer signedness error in Opera before 8.54 allows remote attackers to execute arbitrary code via long values in a stylesheet attribute, which pass a length check. NOTE: a sign extension problem makes the attack easier with shorter strings.

Heap-based buffer overflow in Opera 9.0 and 9.01 allows remote attackers to execute arbitrary code via a long URL in a tag (long link address).

Opera 7.50 and earlier allows remote web sites to provide a "Shortcut Icon" (favicon) that is wider than expected, which could allow the web sites to spoof a trusted domain and facilitate phishing attacks using a wide icon and extra spaces.

Opera does not prevent cookies that are sent over an insecure channel (HTTP) from also being sent over a secure channel (HTTPS/SSL) in the same domain, which could allow remote attackers to steal cookies and conduct unauthorized activities, aka "Cross Security Boundary Cookie Injection."

Opera 7.54 allows remote attackers to cause a denial of service (application crash from memory exhaustion), as demonstrated using Javascript code that continuously creates nested arrays and then sorts the newly created arrays.

Opera 7.54 and earlier uses kfmclient exec to handle unknown MIME types, which allows remote attackers to execute arbitrary code via a shortcut or launcher that contains an Exec entry.

The Javascript engine in Opera 7.23 allows remote attackers to cause a denial of service (crash) by creating a new Array object with a large size value, then writing into that array.

Opera Browser 7.23, and other versions before 7.50, updates the address bar as soon as the user clicks a link, which allows remote attackers to redirect to other sites via the onUnload attribute.

Opera before 7.54 allows remote attackers to modify properties and methods of the location object and execute Javascript to read arbitrary files from the client's local filesystem or display a false URL to the user.

The International Domain Name (IDN) support in Opera 7.54 allows remote attackers to spoof domain names using punycode encoded domain names that are decoded in URLs and SSL certificates in a way that uses homograph characters from other character sets, which facilitates phishing attacks.

The International Domain Name (IDN) support in Epiphany allows remote attackers to spoof domain names using punycode encoded domain names that are decoded in URLs and SSL certificates in a way that uses homograph characters from other character sets, which facilitates phishing attacks.

Opera 7.54 and earlier does not properly validate base64 encoded binary data in a data: (RFC 2397) URL, which causes the URL to be obscured in a download dialog, which may allow remote attackers to trick users into executing arbitrary code.

Opera 8.01 allows remote attackers to cause a denial of service (CPU consumption) via a crafted JPEG image, as demonstrated using random.jpg.