Opera
CVE-2012-4142
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 4.3 (MEDIUM). Attack characteristics: network attack vector, M complexity. EPSS exploitation probability: 0.42%. |
| Exploit ScenarioDerived | A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. |
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Alert meAnalysisAI
Opera before 12.01 on Windows and UNIX, and before 11.66 and 12.x before 12.01 on Mac OS X, ignores some characters in HTML documents in unspecified circumstances, which makes it easier for remote. Rated medium severity (CVSS 4.3), this vulnerability is remotely exploitable. No vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. Opera before 12.01 on Windows and UNIX, and before 11.66 and 12.x before 12.01 on Mac OS X, ignores some characters in HTML documents in unspecified circumstances, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via a crafted document. Affected products include: Opera Opera Browser. Version information: before 12.01.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:M/Au:N/C:N/I:P/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
Opera before 12.01 on Windows and UNIX, and before 11.66 and 12.x before 12.01 on Mac OS X, ignores some characters in HTML documents in unspecified circumstances, which makes it easier for remote attackers to conduct cross-site scripting (XSS) attacks via a crafted document.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)CVE.org
The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not pro
Opera before 12.12 does not properly allocate memory for GIF images, which allows remote attackers to execute arbitrary
Opera before 12.13 allows remote attackers to execute arbitrary code via crafted clipPaths in an SVG document. Rated cri
Opera Mini for Android allows attackers to bypass intended restrictions on .apk file download/installation via an RTLO (
Opera before 11.64 does not properly allocate memory for URL strings, which allows remote attackers to execute arbitrary
Heap-based buffer overflow in Opera before 12.11 allows remote attackers to execute arbitrary code or cause a denial of
Opera before 12.13 allows remote attackers to execute arbitrary code via vectors involving DOM events. Rated critical se
Opera Mini 13 and Opera Stable 36 allow remote attackers to spoof the displayed URL via a crafted HTML document, related
The Opera Mini application through 16.0.14 for iOS has a UXSS vulnerability that can be triggered by performing navigati
Unspecified vulnerability in Opera before 12.15 has unknown impact and attack vectors, related to a "moderately severe i
Unspecified vulnerability in Opera before 12.01 on Windows and UNIX, and before 11.66 and 12.x before 12.01 on Mac OS X,
Unspecified vulnerability in Opera before 12.00 on Mac OS X has unknown impact and attack vectors, related to a "moderat
GitHub PoC
Exploit-DB