How severe is CVE-2021-39878?

CVE-2021-39878 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2021-39878 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39878?

CVE-2021-39878 primarily affects Gitlab. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-39878?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-39878 published?

CVE-2021-39878 was published on 2021-10-05 and last updated on 2026-06-17.

CVE-2021-39878

CVE-2021-39878 is a medium-severity vulnerability in Gitlab with a CVSS 3.x base score of 5.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.8)
CVSS v2: 3.5
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Gitlab
Published: 2021-10-05
Last modified: 2026-06-17

Description

A stored Reflected Cross-Site Scripting vulnerability in the Jira integration in GitLab version 13.0 up to 14.3.1 allowed an attacker to execute arbitrary javascript code.

Frequently asked questions

What is CVE-2021-39878?: A stored Reflected Cross-Site Scripting vulnerability in the Jira integration in GitLab version 13.0 up to 14.3.1 allowed an attacker to execute arbitrary javascript code.
How severe is CVE-2021-39878?: CVE-2021-39878 has a CVSS 3.x base score of 5.8, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2021-39878 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39878?: CVE-2021-39878 primarily affects Gitlab. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-39878?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39878 published?: CVE-2021-39878 was published on 2021-10-05 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*
cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*

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