What is CVE-2021-30151?

CVE-2021-30151 is a medium-severity vulnerability in Contribsys Sidekiq, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-04-06.

How severe is CVE-2021-30151?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2021-30151 known to be exploited?

5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Contribsys Sidekiq

CVE-2021-30151

Sidekiq through 5.1.3 and 6.x through 6.2.0 allows XSS via the queue name of the live-poll feature when Internet Explorer is used.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-04-06 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.042 (90.6th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 90.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.042 · newest: 0.042 · change: 0.000

Affected products

Contribsys Sidekiq
Debian Linux — versions 9.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

References

github.com/mperham/sidekiq/issues/4852 (Exploit, Patch, Third Party Advisory, Issue Tracking)
lists.debian.org/debian-lts-announce/2022/03/msg00015.html (mailing-list, Mailing List, Third Party Advisory)
lists.debian.org/debian-lts-announce/2023/03/msg00011.html (mailing-list)

Frequently asked questions

What is CVE-2021-30151?: CVE-2021-30151 is a medium-severity vulnerability in Contribsys Sidekiq, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2021-04-06.
How severe is CVE-2021-30151?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2021-30151 known to be exploited?: 5 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.