CVE-2021-21339Network attack vector

Session identifier disclosure via cleartext storage

Published Mar 23, 2021 · Updated Aug 3, 2024

Sensitive data exposure in affected TYPO3 CMS releases allows attackers to obtain cleartext identifiers from session storage. The ext:core session-storage component stores user session identifiers without applying an additional cryptographic hash. Exploitation requires a separate flaw, such as SQL injection, that exposes the stored values; the issue is not directly exploitable.

CVSS severity7.5
High
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

Sensitive data exposure in affected TYPO3 CMS releases allows attackers to obtain cleartext identifiers from session storage. The ext:core session-storage component stores user session identifiers without applying an additional cryptographic hash. Exploitation requires a separate flaw, such as SQL injection, that exposes the stored values; the issue is not directly exploitable.

The record

CVE
CVE-2021-21339
Published
Mar 23, 2021
Updated
Aug 3, 2024
Vendor
in2code GmbH
Product
TYPO3 CMS
Classifications
CWE-312, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=>= 10.0.0, <= 10.4.13
  2. Affected versionversion=>= 11.0.0, <= 11.1.0
  3. Affected versionversion=>= 6.2.0, <= 6.2.56
  4. Affected versionversion=>= 7.0.0, <= 7.6.50
  5. Affected versionversion=>= 8.0.0, <= 8.7.39
  6. Affected versionversion=>= 9.0.0, <= 9.5.24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

in2code GmbH · TYPO3 CMSversion=>= 10.0.0, <= 10.4.13; version=>= 11.0.0, <= 11.1.0; version=>= 6.2.0, <= 6.2.56; version=>= 7.0.0, <= 7.6.50; version=>= 8.0.0, <= 8.7.39; version=>= 9.0.0, <= 9.5.24

Published CVSS scores

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5.0NISTAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5TYPO3CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-312Cleartext Storage of Sensitive Information
T1539Steal Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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