Apache WSS4J: Improper Authentication
CVE-2026-88920 is a critical-severity improper authentication vulnerability in Apache WSS4J from Apache, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.0.2, 3.0.6, 2.4.4 as the first without the flaw, so updating Apache WSS4J to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.58% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Apache WSS4J to 4.0.2 or 3.0.6 or 2.4.4, whichever matches your release line, or a later version.
- Update Wss4j to 2.4.4 or 3.0.6 or 4.0.2, whichever matches your release line, or a later version.
- Read the advisory on lists.apache.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache | Apache WSS4J | 4.0.0 up to, but not including, 4.0.2; 3.0.0 up to, but not including, 3.0.6; before 2.4.4 | 4.0.2, 3.0.6, 2.4.4 |
| Apache | Wss4j | before 2.4.4; 3.0.0 up to, but not including, 3.0.6; 4.0.0 up to, but not including, 4.0.2 | 2.4.4, 3.0.6, 4.0.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
An authentication bypass in the DOM security processor in Apache WSS4J allows unauthenticated remote attackers to forge authenticated SOAP messages via a crafted unsigned SAML sender-vouches assertion containing an attacker-controlled key. Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How developers prevent this class of flaw
- Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- openwall.com/lists/oss-security/2026/09/30/10Mailing List, Third Party Advisory
Other vulnerabilities in Apache WSS4J
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.5 High severity
Recent Improper Authentication vulnerabilities
- 7.5 High severity
- 9.1 Critical severity
- 8.1 High severity
- 9.6 Critical severity
- 7.5 High severity
- 7.3 High severity
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