A forged SSL server certificate can be accepted by Opera as a valid certificate

A specially crafted digital certificate can bypass Opera'scertificate signature verification. Forged certificatescan contain any false information the forger chooses, andOpera will still present it as valid. Opera will not presentany warning dialogs in this case, and the security statuswill be th...

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 for UNIX uses a wrapper shell script to start up Opera.This shell script reads the input arguments, like the file namesor URLs that Opera is to open. It also performs some environmentchecks, for example whether Java is available and if so, where itis located.This wrapper script can also run...

Phishing attack possible with a delayed JavaScript prompt – Opera Security Advisories

Phishing attack possible with a delayed JavaScript prompt – Opera Security Advisories OPCOM Team | January 5, 2005 Severity: Moderate/low Problem description A malicious page can be crafted to send the userto his banking site, and shortly afterwardsdisplay a dialog enticing the user to type inhis...

Update your browser: Security fix for Chrome zero-day CVE-2025-10585

News, Security Update your browser: Security fix for Chrome zero-day CVE-2025-10585 Share September 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-2025-10585. We recommend...

Why browsing with Opera’s VPN is safer

Security Why browsing with Opera’s VPN is safer Share July 10th, 2025 A virtual private network VPN is a great way to protect yourself online, especially on public hotspots. Opera is the first major browser to have a built-in, no-log, unlimited browser VPN that is completely free. So how can you...

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

News, Security Update your browser: Security fixes for latest Chrome zero-day Share March 27th, 2025 Hi everyone! The latest patches to the Opera and Opera GX address several recent vulnerabilities, including a zero-day exploit CVE-2025-2783. We recommend updating your browsers to the latest...

How Opera for Android’s revamped ad blocker improves your browsing experience

News, Privacy How Opera for Android’s revamped ad blocker improves your browsing experience Share December 11th, 2024 Hi Opera users! At Opera, we know how intrusive advertising can disrupt your browsing experience by turning it into a frustrating maze of pop-ups. That’s why we have included a...

OpenSSL 3.0.7 security fix: Should Opera users be worried?

Security OpenSSL 3.0.7 security fix: Should Opera users be worried? Share November 3rd, 2022 Hi everyone! The OpenSSL 3.0.7 security-fix release fixes high-priority vulnerabilities in the OpenSSL open-source cryptography library, specifically CVE-2022-3602 and CVE-2022-3786. The vulnerabilities...

Fuzzing HTTP Proxies: Privoxy, Part 1

Research Fuzzing HTTP Proxies: Privoxy, Part 1 Share May 17th, 2021 Here at Opera, we’re always looking for ways to improve the browsing experience of our users with speed and usability. Perhaps more importantly though, we also look for ways to improve users’ privacy and security. While we...

Certificate update

Security Certificate update Share December 9th, 2013 Last week we became aware of the existence of several unauthorized security certificates, issued in violation of rules for creation of such certificates. The certificates chained back to a French certificate authority, ANSSI, and had been signe...

Unexpected changes in tab focus can be used to run programs from the Internet

Tabs may be used to obscure a download dialog that is visible in another tab. The dialog will allow the user to choose to run downloaded executables directly. If the tab is closed or hidden at the moment that a user was about to click, they can end up clicking on the buttons in the dialog, causin...

File inputs can disclose the path to selected files

When a file is selected in a file upload input, the path to that file is not exposed through the input's value property. This is done to protect any sensitive information which may be contained in the directory names. When manipulated by DOM this information should also not be exposed. Certain DO...

*.com accepted as wildcard match in SSL/TLS name matching

Certificate authorities are expected to vet all certificate registrations, but may fail to prevent fraudulent or erroneous registrations. Certificates which use a wild card immediately before the top level domain, or nulls in the domain name, may pass validation checks in Opera. Sites using such...

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...

Specially crafted JPEG images can be used to execute arbitrary code

Specially crafted JPEG images can cause Opera to corrupt memory and crash. Successful exploitation can lead to execution of arbitrary code...

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

Certain constructs are not escaped correctly by Opera's History Search results. These can be used to inject scripts into the page, which can then be used to look through the user's browsing history, including the contents of the pages they have visited. These may contain sensitive information...

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...

The links panel can allow cross-site scripting

The links panel shows links in all frames on the current page, including links with JavaScript URLs. When a page is held in a frame, the script is incorrectly executed on the outermost page, not the page where the URL was located. This can be used to execute scripts in the context of an unrelated...

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...

Image properties can be used to execute scripts – Opera Security Advisories

Image properties can be used to execute scripts – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Highly Severe Problem Description Image properties can contain custom comments. When displaying the image properties, Opera can be tricked into treating the comments as script. This...

Vulnerability in Opera's use of kfmclient

The kfmclient is a part of the KDE desktop environment.It inspects the file given to it to determine its MIMEtype, and performs the action assigned to that MIME typein KDE's configuration. If the file type is an executable,kfmclient may execute it.Opera will not save downloaded files with the...

Malicious setRequestHeader cross-site vulnerability

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

How Opera’s Security team helps make the web safer through responsible disclosure

Security How Opera’s Security team helps make the web safer through responsible disclosure Share April 17th, 2026 Hi everyone! At Opera, we have 30 years of experience in building safe and secure browsers. Our seasoned Security team collaborates internally as well as with external researchers to...

Opera Browser for Android

Research Opera Browser for Android Share May 21st, 2021 In this episode of theOpera Bug Bounty series, we introduce Opera for Android, our main product for the Android platform. What is Opera for Android Opera for Android is a Chromium-based browser that prides itself on a user-friendly and good...

To VPN or not to VPN?

Security To VPN or not to VPN? Share October 29th, 2020 Alice and Bob use VPN to fight Mallory, an inquisitive sysadmin. TL;DR: skip to the conclusions to see what Alice learned. The Privacy Problem Alice and Bob recently met Mallory, who works at the cable company providing internet access to th...

Unjam the logjam

Security Unjam the logjam Share June 9th, 2015 When a browser and website communicate over a secure connection, they encrypt and decrypt the data using a shared symmetric encryption key; the same key is used for encryption and decryption. In order for the browser and server to make sure they use...

Private video streams can be intercepted – Opera Security Advisories

Private video streams can be intercepted – Opera Security Advisories OPCOM Team | October 6, 2010 Severity Moderate Description Video content may be used as filler content for a HTML5 canvas, if the video format is natively supported by Opera. If the video and page are from the same site, the...

Unexpected changes in tab focus can be used to run programs from the Internet – Opera Security Advisories

Unexpected changes in tab focus can be used to run programs from the Internet – Opera Security Advisories OPCOM Team | August 12, 2010 Severity Moderate Description Tabs may be used to obscure a download dialog that is visible in another tab. The dialog will allow the user to choose to run...

TLS protocol vulnerable to Man In The Middle attack – Opera Security Advisories

TLS protocol vulnerable to Man In The Middle attack – Opera Security Advisories OPCOM Team | June 29, 2010 Summary A vulnerability has been discovered in all current versions of the SSL and TLS protocols, that may allow an attacker to inject data and instructions into the HTTPS connection and tri...

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...

Cross-domain data theft with CSS load – Opera Security Advisories

Cross-domain data theft with CSS load – Opera Security Advisories OPCOM Team | January 11, 2010 Summary CSS can be loaded cross-domain, and in some cases it is be possible to read the data pointed to, leading to the possibility of cross-domain data theft. Severity Moderate Opera’s response Opera...

Cross-domain data theft with CSS load

CSS can be loaded cross-domain, and in some cases it is be possible to read the data pointed to, leading to the possibility of cross-domain data theft...

Certain domain names can allow execution of arbitrary code

Specially crafted domain names can cause a memory corruption in Opera, which may lead to a crash. Successful exploitation can lead to execution of arbitrary code...

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...

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...

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...

Representation of DOM attribute values could allow cross-site scripting – Opera Security Advisories

Representation of DOM attribute values could allow cross-site scripting – Opera Security Advisories OPCOM Team | December 16, 2008 Severity Moderately Severe Problem Description When XML is imported into a document, its attribute values are not correctly presented to the DOM. This can allow their...

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...

Double-clicking a link can run a program from the Internet

Links in Web pages only require a single click. When a userdouble-clicks on a Web link, that action is taken as twoseparate clicks: One to follow the link, and the other toany dialog that might appear where the link was.A specially crafted page can place the link so that the"Open" button in the...

How your Opera browser keeps you safe from spyware and other cyber threats

Privacy, Security How your Opera browser keeps you safe from spyware and other cyber threats Share August 11th, 2023 Hi everyone! In our digital age, your online security is often under threat. From phishing scams to spyware and direct hacking attempts, your personal data is often in the crosshai...

Earn up to $10K from the Opera Bug Bounty program

Security Earn up to $10K from the Opera Bug Bounty program Share April 30th, 2021 Join the Opera Bug Bounty program, find vulnerabilities in scope, tell us how you did it, and collect rewards. We pay up to $10K for confirmed high-value submissions. Opera has two bug bounty programs operated by...

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...

Breach incident

News Breach incident Share December 11th, 2013 At Opera, we strive to be open, and we want to continue this tradition, by sharing with you what happens here. High profile companies like Opera are under continuous attack by hackers trying to break into their systems, and we want to tell you about ...

Security changes and features of Opera 18

News Security changes and features of Opera 18 Share December 4th, 2013 Opera 18 is now out on the stable channel, so we wanted to take a moment to go through some of the new features from a security perspective. Media Access One of the new features is media access. That is; camera and microphone...

Replaced code signing certificate – Opera Security Advisories

Opera Software recently experienced an attack on the internal infrastructure. Following best practices, Opera Software is replacing signing certificates in Opera with newly issued certificates. Certificates in Opera include the code signing certificate for desktop binaries and the signing...

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...

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,...

TLS certificates can be used to execute arbitrary code

When connecting to a TLS-protected website, Opera parses the X.509 certificate. If a site uses a specially crafted Subject Alternative Name in the certificate, it can cause Opera to crash. To inject code, additional means will have to be employed...