CVE-2021-43847 | Authorization Bypass in Space Invite in HumHub

Exp

HumHub is an open-source social network kit written in PHP. Prior to HumHub version 1.10.3 or 1.9.3, it could be possible for registered users to become unauthorized members of private Spaces. Versions 1.10.3 and 1.9.3 contain a patch for this issue.

Published: 2021-12-20 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-43847 is rated High Exploit Risk (64.1/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.18%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2021-43847

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-43847

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 0.33% 1.18% +0.85%
2 2025-11-21 0.37% 0.33% -0.04%
3 2025-11-18 — 0.37% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-43847

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2021-43847

Affected software / configurations for CVE-2021-43847

Vendor Product Version Raw CPE
humhub humhub < 1.9.3 cpe:2.3:a:humhub:humhub:*:*:*:*:*:*:*:*
humhub humhub >= 1.10.0, < 1.10.3 cpe:2.3:a:humhub:humhub:*:*:*:*:*:*:*:*

References for CVE-2021-43847

URL Tags
https://github.com/humhub/humhub/pull/5473 Patch Third Party Advisory
https://github.com/humhub/humhub/releases/tag/v1.10.3 Release Notes Third Party Advisory
https://github.com/humhub/humhub/releases/tag/v1.9.3 Release Notes Third Party Advisory
https://github.com/humhub/humhub/security/advisories/GHSA-f5hc-5wfr-7v74 Exploit Third Party Advisory
https://huntr.dev/bounties/943dad83-f0ed-4c74-ba81-7dfce7ca0ef2/ Exploit Issue Tracking Patch Third Party Advisory
cvelogic Threat Intelligence