CVE-2021-20788Network attack vector

Internal web disclosure and port scanning via bookmarks

Published Jul 28, 2021 · Updated Aug 3, 2024

Server-side request forgery in affected GroupSession editions before 5.1.0 allows remote authenticated users to scan ports or read internal web data. The bookmark function sends server-side requests that can reach internal hosts and arbitrary ports; public advisories do not identify the affected handler or missing validation. Any authenticated account with bookmark access can originate requests from the GroupSession server, exposing reachable internal web content and port status.

CVSS severity5.0
Medium
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Server-side request forgery in affected GroupSession editions before 5.1.0 allows remote authenticated users to scan ports or read internal web data. The bookmark function sends server-side requests that can reach internal hosts and arbitrary ports; public advisories do not identify the affected handler or missing validation. Any authenticated account with bookmark access can originate requests from the GroupSession server, exposing reachable internal web content and port status.

The record

CVE
CVE-2021-20788
Published
Jul 28, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-918, T1046
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
5.0JPCERT/CC and IPACVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
4.0JPCERT/CC and IPAAV:N/AC:L/Au:S/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1046Network Service Discovery

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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