CVE-2021-33490Public exploitNetwork attack vector

Session hijacking via unsanitized malformed signature snippets

Published Nov 22, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in the OX App Suite backend through 7.10.5 allows remote authenticated users to hijack user sessions. The backend snippet sanitizer fails to neutralize script-bearing malformed HTML before storing and rendering the snippet as a shared mail signature. Exploitation requires access to the victim's account or the same OX context and requires the victim to select the signature; the script then runs in the victim's web session.

CVSS severity3.5
Low
EPSS probability1.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in the OX App Suite backend through 7.10.5 allows remote authenticated users to hijack user sessions. The backend snippet sanitizer fails to neutralize script-bearing malformed HTML before storing and rendering the snippet as a shared mail signature. Exploitation requires access to the victim's account or the same OX context and requires the victim to select the signature; the script then runs in the victim's web session.

The record

CVE
CVE-2021-33490
Published
Nov 22, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, CWE-80, T1204
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 22, 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

6.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:N/I:P/A:N
3.5OX Software GmbHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
T1204User Execution

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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