CVE-2021-32676Public exploitNetwork attack vector

Guest session hijacking via unchanged authentication cookie

Published Jun 16, 2021 · Updated Aug 3, 2024

Session fixation in Nextcloud Talk before 9.0.10, 10.0.8, and 11.2.2 allows remote attackers to hijack password-protected guest chats. The shared-chat password-authentication path preserves the pre-authentication session cookie instead of issuing a new identifier. Exploitation requires obtaining a guest's cookie before the guest submits the room password; reuse then grants the guest's authenticated chat access.

CVSS severity6.5
Medium
EPSS probability0.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Nextcloud Talk before 9.0.10, 10.0.8, and 11.2.2 allows remote attackers to hijack password-protected guest chats. The shared-chat password-authentication path preserves the pre-authentication session cookie instead of issuing a new identifier. Exploitation requires obtaining a guest's cookie before the guest submits the room password; reuse then grants the guest's authenticated chat access.

The record

CVE
CVE-2021-32676
Published
Jun 16, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-384, T1550.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 16, 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=>= 10.0.0, < 10.0.8
  2. Affected versionversion=>= 11.0.0, < 11.2.2
  3. Affected versionversion=< 9.0.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=>= 10.0.0, < 10.0.8; version=>= 11.0.0, < 11.2.2; version=< 9.0.10

Published CVSS scores

4.0NIST NVDAV:N/AC:L/Au:S/C:P/I:N/A:N
6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-384Session Fixation
T1550.004Use Alternate Authentication Material: Web Session Cookie

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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