CVE-2026-27614
CVE-2026-27614
Weakness (CWE)
CVSS Vector
v3.1- Attack Vector
- Network
- Attack Complexity
- Low
- Privileges Required
- None
- User Interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Description
Bugsink is a self-hosted error tracking tool. In versions prior to 2.0.13, an unauthenticated attacker who can submit events to a Bugsink project can store arbitrary JavaScript in an event. The payload executes only if a user explicitly views the affected Stacktrace in the web UI. When Pygments returns more lines than it was given (a known upstream quirk that triggers with Ruby heredoc-style input), `_pygmentize_lines()` in `theme/templatetags/issues.py:75-77` falls back to returning the raw input lines. `mark_safe()` at line 111-113 is then applied unconditionally - including to those unsanitized raw lines. Since DSN endpoints are public by Sentry protocol, no account is needed to inject. The payload sits in the database until an admin looks at the event. Successful exploitation requires that the attacker to be able to submit events to the project (i.e. knows the DSN or can access a client that uses it), the Bugsink ingest endpoint is reachable to the attacker, and an administrator explicitly views the crafted event in the UI. Under those conditions, the attacker can execute JavaScript in the administrator’s browser and act with that user’s privileges within Bugsink. Version 2.0.13 fixes the vulnerability.
Comprehensive Technical Analysis of CVE-2026-27614
1. Vulnerability Assessment and Severity Evaluation
CVE ID: CVE-2026-27614
Description:
Bugsink, a self-hosted error tracking tool, is vulnerable to a stored Cross-Site Scripting (XSS) attack in versions prior to 2.0.13. An unauthenticated attacker can submit events containing arbitrary JavaScript, which executes when an administrator views the affected Stacktrace in the web UI. The vulnerability arises from improper sanitization of input lines returned by the _pygmentize_lines() function in theme/templatetags/issues.py.
CVSS Score: 9.3 (Critical)
Severity Evaluation: The CVSS score of 9.3 indicates a critical vulnerability. This high score is due to the potential for unauthenticated attackers to execute arbitrary JavaScript in an administrator's browser, leading to significant security risks such as privilege escalation and data exfiltration.
2. Potential Attack Vectors and Exploitation Methods
Attack Vectors:
- Unauthenticated Event Submission: An attacker can submit malicious events to a Bugsink project if they know the DSN (Data Source Name) or have access to a client that uses it.
- Public DSN Endpoints: Since DSN endpoints are public by Sentry protocol, no account is needed to inject malicious events.
- Administrator Interaction: The payload executes when an administrator views the crafted event in the web UI.
Exploitation Methods:
- Crafting Malicious Events: The attacker crafts an event with embedded JavaScript.
- Submitting Events: The attacker submits the malicious event to the Bugsink project.
- Waiting for Admin Interaction: The payload remains dormant in the database until an administrator views the event, triggering the execution of the JavaScript.
3. Affected Systems and Software Versions
Affected Software:
- Bugsink versions prior to 2.0.13
Affected Systems:
- Any system running the vulnerable versions of Bugsink.
- Systems where administrators have access to the web UI and can view event Stacktraces.
4. Recommended Mitigation Strategies
Immediate Actions:
- Upgrade to Version 2.0.13: Immediately upgrade to Bugsink version 2.0.13 or later, which includes the fix for this vulnerability.
- Restrict Access: Temporarily restrict access to the Bugsink web UI until the upgrade is complete.
- Monitor Logs: Monitor logs for any suspicious activity or unauthorized event submissions.
Long-Term Strategies:
- Input Sanitization: Ensure all input is properly sanitized and validated.
- Regular Updates: Implement a regular update and patch management process.
- Security Training: Provide security training for administrators to recognize and avoid potential XSS attacks.
5. Impact on Cybersecurity Landscape
Immediate Impact:
- Privilege Escalation: Attackers can gain administrative privileges within Bugsink.
- Data Exfiltration: Sensitive data can be exfiltrated through the execution of malicious JavaScript.
- Compromised Integrity: The integrity of the error tracking system is compromised, leading to potential misinformation and incorrect error handling.
Long-Term Impact:
- Increased Awareness: This vulnerability highlights the importance of input sanitization and regular updates.
- Enhanced Security Measures: Organizations may implement stricter security protocols and more frequent audits.
- Community Response: The cybersecurity community may develop additional tools and best practices to mitigate similar vulnerabilities.
6. Technical Details for Security Professionals
Vulnerable Code:
_pygmentize_lines()intheme/templatetags/issues.py:75-77mark_safe()at line 111-113
Technical Analysis:
- Pygments Quirk: Pygments returns more lines than it was given when processing Ruby heredoc-style input.
- Unsanitized Input: The
_pygmentize_lines()function falls back to returning raw input lines, which are then marked as safe without proper sanitization. - Execution Trigger: The payload executes when an administrator views the affected Stacktrace in the web UI.
Mitigation Code:
- Ensure that all input is properly sanitized before being marked as safe.
- Implement additional checks to handle cases where Pygments returns more lines than expected.
References:
By addressing this vulnerability promptly and implementing robust security measures, organizations can mitigate the risks associated with CVE-2026-27614 and enhance their overall cybersecurity posture.