CVE-2021-21823Public exploitNetwork attack vector

Information disclosure via substring friend search

Published Aug 20, 2021 · Updated Aug 3, 2024

Information disclosure in Komoot 10.26.9 through 11.1.11 allows remote attackers to enumerate email addresses and profile IDs. The Friend finder matches attacker-supplied substrings against usernames, enabling broad domain searches and digit-by-digit profile ID enumeration. No authentication or user interaction is required, and discoverability is enabled by default, although users can disable it.

CVSS severity7.5
High
EPSS probability0.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Komoot 10.26.9 through 11.1.11 allows remote attackers to enumerate email addresses and profile IDs. The Friend finder matches attacker-supplied substrings against usernames, enabling broad domain searches and digit-by-digit profile ID enumeration. No authentication or user interaction is required, and discoverability is enabled by default, although users can disable it.

The record

CVE
CVE-2021-21823
Published
Aug 20, 2021
Updated
Aug 3, 2024
Vendor
Komoot GmbH
Product
Komoot
Classifications
CWE-200, CWE-359, T1589.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Komoot GmbH Komoot 10.26.9 , Komoot GmbH Komoot 11.0.14 ,Komoot GmbH Komoot 11.1.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Komoot GmbH · Komootversion=Komoot GmbH Komoot 10.26.9 , Komoot GmbH Komoot 11.0.14 ,Komoot GmbH Komoot 11.1.11

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.3Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CWE-359Exposure of Private Information ('Privacy Violation')
T1589.002Gather Victim Identity Information: Email Addresses

Public exploit references

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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