CVE-2026-27614 Bugsink is vulnerable to Stored XSS via Pygments fallback in stacktrace rendering
An unauthenticated attacker can inject JavaScript into error events, which executes in an administrator's browser when viewed, allowing privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-27614?
CVE-2026-27614 is a critical cross-site scripting vulnerability in bugsink, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-79
Which versions are affected by CVE-2026-27614?
3 open source packages ship an affected version, including bugsink. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
bugsink PyPI | All versions | 2.0.13 |
bugsink PyPI | All versions | 2.0.13 |
bugsink PyPI | All versions | 2.0.13 |
Products include Bugsink Bugsink.
How do I fix CVE-2026-27614?
Upgrade bugsink to 2.0.13 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-27614 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27614 exists.
Other vulnerabilities in bugsink
Sources
Also known as GHSA-vp6q-7m36-pq3w, PYSEC-2026-301.