CVE-2021-39910

An issue has been discovered in GitLab CE/EE affecting all versions starting from 12.6 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. GitLab was vulnerable to HTML Injection through the Swagger UI feature.

Published: 2021-12-13 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-39910 is rated Low Risk (31/100): CVSS Low severity, with medium exploitation likelihood (EPSS 0.95%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-39910

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.18% 0.95% +0.78%
2 2025-12-24 0.30% 0.18% -0.12%
3 2025-11-21 — 0.30% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-39910

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
2.6 3.1 LOW
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 1.2 1.4 [email protected]
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-39910

OS Trackers for CVE-2021-39910

vendor priority summary link
debian not yet assigned CVE-2021-39910 not yet assigned priority: Debian including 1 source packages (gitlab), 1 status rows across 1 suites (sid): resolved 1. https://security-tracker.debian.org/tracker/CVE-2021-39910
ubuntu low CVE-2021-39910 low priority: Ubuntu including 1 source packages (gitlab), 12 status rows across 12 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): DNE 9, ignored 2, needs-triage 1. https://ubuntu.com/security/CVE-2021-39910

Affected software / configurations for CVE-2021-39910

Vendor Product Version Raw CPE
gitlab gitlab >= 12.6.0, < 14.3.6 cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*
gitlab gitlab >= 12.6.0, < 14.3.6 cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*
gitlab gitlab >= 14.4.0, < 14.4.4 cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*
gitlab gitlab >= 14.4.0, < 14.4.4 cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*
gitlab gitlab >= 14.5.0, < 14.5.2 cpe:2.3:a:gitlab:gitlab:*:*:*:*:community:*:*:*
gitlab gitlab >= 14.5.0, < 14.5.2 cpe:2.3:a:gitlab:gitlab:*:*:*:*:enterprise:*:*:*

References for CVE-2021-39910

cvelogic Threat Intelligence