What is CVE-2021-43956?

CVE-2021-43956 is a medium-severity vulnerability in Atlassian Crucible, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 6.1/10. Published 2022-03-16.

How severe is CVE-2021-43956?

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

Prototype Pollution in Atlassian Crucible

CVE-2021-43956

The jQuery deserialize library in Fisheye and Crucible before version 4.8.9 allowed remote attackers to to inject arbitrary HTML and/or JavaScript via a prototype pollution vulnerability.

Vulnerability class: Prototype Pollution

Published 2022-03-16 · 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: 0.007 (53.4th percentile), scored 2026-10-18.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Atlassian Crucible — versions unspecified
Atlassian Fisheye — versions unspecified

Weakness classification (CWE)

CWE-1321 — Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

References

jira.atlassian.com/browse/FE-7395 (Issue Tracking, Vendor Advisory)
jira.atlassian.com/browse/CRUC-8531 (Issue Tracking, Vendor Advisory)

Frequently asked questions

What is CVE-2021-43956?: CVE-2021-43956 is a medium-severity vulnerability in Atlassian Crucible, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 6.1/10. Published 2022-03-16.
How severe is CVE-2021-43956?: Medium severity. CVSS v3 base score is 6.1 out of 10.