Sites using revoked intermediate certificates might be shown as secure

Opera does not check the revocation status for intermediate certificates not served by the server. If the intermediate is revoked, this might not impact the security rating in Opera, and the site might be shown as secure...

TLS certificates can be used to execute arbitrary code – Opera Security Advisories

TLS certificates can be used to execute arbitrary code – Opera Security Advisories OPCOM Team | February 13, 2009 Severity Highly Severe Problem Description When connecting to a TLS-protected website, Opera parses the X.509 certificate. If a site uses a specially crafted Subject Alternative Name ...

Feed subscription can cause the wrong page address to be displayed

It has been reported that when a user subscribes to a news feed using the feed subscription button, the page address can be changed. This causes the address field not to update correctly. Although this can mean that that misleading information can be displayed in the address field, it can only...

Resized canvas patterns can cause Opera to execute arbitrary code – Opera Security Advisories

Resized canvas patterns can cause Opera to execute arbitrary code – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Moderately Severe Problem Description HTML CANVAS elements can use scaled images as patterns. With suitable scaling manipulation of the image, a script can cause...

Feed subscription can cause the wrong page address to be displayed – Opera Security Advisories

Feed subscription can cause the wrong page address to be displayed – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Not Severe Problem Description It has been reported that when a user subscribes to a news feed using the feed subscription button, the page address can be changed...

Character Encoding Inheritance in iframes Can Enable Cross-Site Scripting

Pages displayed inside an iframe will inherit the character encodingof the parent page, unless they specify their own character encoding.A malicious page that uses the UTF-7 character encoding can includeother sites, for example inside iframes. This can be exploited toperform cross-site scripting...

Startup crash can allow execution of arbitrary code

When Opera is registered as a handler for a given protocol, it can be started by external applications. In some cases, being started in this way can cause Opera to crash. To inject code, additional techniques will have to be employed...

Startup crash can allow execution of arbitrary code – Opera Security Advisories

Startup crash can allow execution of arbitrary code – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Extremely Severe Problem Description When Opera is registered as a handler for a given protocol, it can be started by external applications. In some cases, being started in this...

data: URLs can spoof trusted trusted sites

data: URLs embed data inside them, instead of linking to an externalresource. Opera can mistakenly display the end of a data URL insteadof the beginning. This allows an attacker to spoof the URL of atrusted site...

Malicious WMF files stored in Opera’s cache can infect Windows – Opera Security Advisories

Malicious WMF files stored in Opera’s cache can infect Windows – Opera Security Advisories OPCOM Team | January 13, 2006 Summary Windows Meta Files .wmf can contain executable code. A specially craftedWMF file can infect Microsoft Windows with malicious software when it is openedwith Windows’ own...

Opera may execute command line embedded in URLs – Opera Security Advisories

Opera may execute command line embedded in URLs – Opera Security Advisories OPCOM Team | November 23, 2005 Summary Opera will execute command lines embedded in the URL when anotherprogram uses Opera to open a link. This affects UNIX versions ofOpera Linux/FreeBSD/Solaris. Severity: High Problem...

Malicious setRequestHeader cross-site vulnerability

A malicious setRequestHeader can be used to stealuser credentials and inject cross-site JavaScript...

Internationalized domain names (IDN) can be used for spoofing. – Opera Security Advisories

Internationalized domain names IDN can be used for spoofing. – Opera Security Advisories OPCOM Team | February 25, 2005 Summary Opera supports internationalized domain names IDN, which allowsfor example Russian or Chinese domain names to be written in theirown native scripts. However, this also...

Update your browser: Security fix for Chrome zero-day CVE-2025-14174

News, Security Update your browser: Security fix for Chrome zero-day CVE-2025-14174 Share December 18th, 2025 Hi everyone! The latest patches to Opera, Opera GX, Opera Air, and Opera for Android address several recent vulnerabilities, including a zero-day exploit CVE-2025-14174. We recommend...

Prompt injection in Opera Neon: Rapid response through responsible disclosure

Security Prompt injection in Opera Neon: Rapid response through responsible disclosure Share October 23rd, 2025 Hi Opera users, This week, we were able to address a real-world security scenario on Opera Neon thanks to the work of a security researcher team. The researchers reached out to us throu...

Update your browser: Security fix for Chrome zero-day CVE-2025-6554

News, Security Update your browser: Security fix for Chrome zero-day CVE-2025-6554 Share July 3rd, 2025 Hi everyone! The latest patches to the Opera, Opera GX, Opera Air, and Opera for Android address several recent vulnerabilities, including a zero-day exploit CVE-2025-6554. We recommend updatin...

Opera’s Security team at Barcelona Cybersecurity Congress 2023

Security Opera’s Security team at Barcelona Cybersecurity Congress 2023 Share February 9th, 2023 Hello readers! If you follow our Security team’s Twitter account it’s here, by the way!, you’ll have noticed we were busy last week meeting cybersecurity enthusiasts and professionals at this year’s...

New home for the Security Group blog

News New home for the Security Group blog Share October 31st, 2013 Welcome to the new home of the Opera Security Group. We have changed our blogging platform. For more more information regarding the switch, please see this post. If you received this blog post in your feed reader, you do not need ...

Reloads and redirects can allow spoofing and cross site scripting – Opera Security Advisories

Reloads and redirects can allow spoofing and cross site scripting – Opera Security Advisories OPCOM Team | October 6, 2010 Severity Critical Description Scripts on a page are supposed to be restricted so that they can only interact with other pages from the same domain and security context...

Malicious DLL files can be unintentionally loaded and allowed to run arbitrary code

Opera uses dynamic link libraries DLLs of its own, and several provided by the host operating system or plug-ins. In some cases, Opera searches for these DLLs in the same location as a resource that is being loaded, and if a malicious DLL is located, it will load that as if it were a trusted DLL...

Opera security upgrade for Linux, Solaris and FreeBSD

A security issue in the Adobe Flash Player running in Opera on Linux, Solaris or FreeBSD has been found. Details about the vulnerability will be disclosed at a later date...

Resized canvas patterns can cause Opera to execute arbitrary code

HTML CANVAS elements can use scaled images as patterns. With suitable scaling manipulation of the image, a script can cause Opera to crash. This crash can sometimes cause memory corruption. To inject code, additional techniques will have to be employed...

External news readers and e-mail clients can be used to execute arbitrary code

If a user has configured Opera to use an external newsgroup client or e-mail application, specially crafted Web pages can cause Opera to run that application incorrectly. In some cases this can lead to execution of arbitrary code...

Opera security advisory 2004-12-10 – Opera Security Advisories

Opera security advisory 2004-12-10 – Opera Security Advisories OPCOM Team | February 9, 2007 Opera security advisory Named frames or windows can be hi-jacked by malicious frames or windows. Periods in the file name and non-breaking spaces in the Content-Type header can make the save/open dialog...

Data Privacy Day: Inside the role of Data Protection Officer at Opera

Privacy Data Privacy Day: Inside the role of Data Protection Officer at Opera Share January 28th, 2026 Privacy matters all year round. But every January, Data Privacy Day is a great opportunity to learn more about data privacy and protection, and to highlight their importance for everyone in the...

Update your browser: Security fix for Chrome zero-day CVE-2025-13223

News, Security Update your browser: Security fix for Chrome zero-day CVE-2025-13223 Share November 20th, 2025 Hi everyone! The latest patches to Opera, Opera GX, Opera Air, and Opera for Android address several recent vulnerabilities, including a zero-day exploit CVE-2025-13223. We recommend...

Update your browser: Security fix for Chrome zero-day CVE-2025-6558

News, Security Update your browser: Security fix for Chrome zero-day CVE-2025-6558 Share July 17th, 2025 Hi everyone! The latest patches to the Opera, Opera GX, and Opera Air address several recent vulnerabilities, including a zero-day exploit CVE-2025-6558. We recommend updating your browsers to...

Addressing the “CrossBarking” vulnerability discovered in collaboration with Guardio

News, Security Addressing the “CrossBarking” vulnerability discovered in collaboration with Guardio Share October 30th, 2024 Hi Opera users! Over time, we have shared details about how we approach security vulnerabilities, and especially how we work with external security researchers to identify...

Update your browser: Security fixes for latest Chrome zero-day

News, Security Update your browser: Security fixes for latest Chrome zero-day Share January 18th, 2024 Hi everyone! The latest patches to the Opera, Opera GX, Opera Crypto, and Opera for Android browsers address several recent vulnerabilities, including a zero-day exploit CVE-2024-0519. We...

Update your browser: Security fixes for latest Chrome bugs

News, Security Update your browser: Security fixes for latest Chrome bugs Share December 1st, 2023 Hi everyone! The latest patches to the Opera, Opera GX, and Opera Crypto browsers address several recent vulnerabilities, including a zero-day exploit CVE-2023-6345. We recommend updating your...

Address bar spoofing in Opera Mini for Android – Opera Security Advisories

Opera Mini for Android before version 52.2 is vulnerable to an address bar spoofing attack. The vulnerability allows a malicious page to trick the browser into showing an address of a different page. This may allow the malicious page to impersonate another page and trick a user into providing...

Opera server breach incident

News Opera server breach incident Share August 26th, 2016 Earlier this week, we detected signs of an attack where access was gained to the Opera sync system. This attack was quickly blocked. Our investigations are ongoing, but we believe some data, including some of our sync users’ passwords and...

Misissued certificates

Security Misissued certificates Share October 29th, 2015 Recently, Google found a google.com pre-certificate in a CT log, without having ordered one. This lead to a series of incidents, also involving Opera and its security team. The backstory Google promptly contacted Symantec who had issued the...

Heartbleed and other heartaches

Security Heartbleed and other heartaches Share April 11th, 2014 As has been reported extensively already, OpenSSL just fixed a serious vulnerability, dubbed Heartbleed. OpenSSL is used in a variety of products used on the internet, including Opera products and servers. We want to share with you h...

TLS response timings can indicate network contents – Opera Security Advisories

When Opera receives incorrectly encrypted network data, Opera will detect this, and let the sender know that the data was not understood. Such encrypted error responses are marginally faster than regular responses. An attacker with access to the network, can by replacing network data measure...

Specially crafted WebP images can be used to disclose random chunks of memory – Opera Security Advisories

WebP images may be used as fill patterns in a HTML5 Canvas, and the values of each pixel in the image can then be intentionally read using scripts. Specially crafted WebP images may specify the wrong size for certain parts of their data, which causes Opera to read data from the wrong positions in...

Changing from a single-user to a multi-user installation on Windows (rev2) – Opera Security Advisories

Changing from a single-user to a multi-user installation on Windows rev2 – Opera Security Advisories OPCOM Team | January 5, 2012 If you received the error message “There was a problem initializing Opera Mail. Engine Init Failed”, it may mean that you have a stand-alone USB installation of Opera...

Malicious DLL files can be unintentionally loaded and allowed to run arbitrary code – Opera Security Advisories

Malicious DLL files can be unintentionally loaded and allowed to run arbitrary code – Opera Security Advisories OPCOM Team | September 8, 2010 Severity High Description Opera uses dynamic link libraries DLLs of its own, and several provided by the host operating system or plug-ins. In some cases,...

Heap buffer overflow in HTML5 canvas can be used to execute arbitrary code

Performing some painting operations on a canvas while certain transformations are being applied in Opera may result in heap buffer overflows. In most cases Opera will just freeze or terminate, but in some cases this could lead to a crash which could be used to execute code. To inject code,...

Opera may be used as a vector for a font issue in the underlying operating system

A flaw in the font handling on the Windows operating system has been fixed by Microsoft. On unpatched systems, Web fonts may be used to exploit this issue through Opera...

Opera may be used as a vector for a font issue in the underlying operating system – Opera Security Advisories

Opera may be used as a vector for a font issue in the underlying operating system – Opera Security Advisories OPCOM Team | June 19, 2010 Affected versions This vulnerability may be targeted through Opera for Windows. Severity Extremely Severe Description A flaw in the font handling on the Windows...

Heap buffer overflow in string to number conversion – Opera Security Advisories

Passing very long strings through the string to number conversion using JavaScript in Opera may result in heap buffer overflows. This also affects the dtoa routine, and was reported in CVE-2009-0689. In most cases Opera will just freeze or terminate, but in some cases this could lead to a crash...

Opera may allow scripts to access feeds

Opera may allow scripts to run on the feed subscription page, thereby gaining access to the feeds object. This can be used for automatic subscription of feeds, or reading other feeds...

Certain characters can be used to allow cross-site scripting

When accepting HTML content from untrusted users, Web sites sometimes employ some kind of filtering to ensure that the content cannot contain scripts. If the content is to be used inside an HTML attribute, characters that separate attributes need to be filtered out to prevent scripted attributes...

History Search can reveal browsing history – Opera Security Advisories

History Search can reveal browsing history – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Extremely Severe Platforms All desktop versions Problem Description Certain constructs are not escaped correctly by Opera’s History Search results. These can be used to inject scripts in...

Feed preview can reveal contents of unrelated news feeds

When Opera is previewing a news feed, some scripts are not correctly blocked. These scripts are able to subscribe the user to any feed URL that the attacker chooses, and can also view the contents of any feeds that the user is subscribed to. These may contain sensitive information...

Opera security upgrade for Linux, Solaris and FreeBSD – Opera Security Advisories

Opera security upgrade for Linux, Solaris and FreeBSD – Opera Security Advisories OPCOM Team | December 16, 2008 Summary Opera 9.20 has a highly recommended security upgrade for users of the Adobe Flash Player on Linux, Solaris and FreeBSD Severity Highly critical Problem description A security...

Rich editing allows cross domain scripting

Rich editing using designMode allows page contents to be edited. Pages can use this ability to inject scripts into pages from other domains. This allows cross domain scripting...

Newsfeed prompt can cause Opera to execute arbitrary code

When Opera encounters a newsfeed source on a Web page, it prompts to add the source as a newsfeed. A script can manipulate the feed source in a way that can cause Opera to crash. The crash is caused by an erroneous memory access. To inject code, additional techniques will have to be employed...

Opera's HTTP authentication cuts off long server names at the end

Opera's HTTP authentication dialog is displayed when the user enters a Web pagethat requires a login name and a password. To inform the user which server itwas that asked for login credentials, the dialog displays the server name.The user has to see the entire server name. A truncated name can be...