VulnerabilityPublished 23 Sep 2026

CVE-2026-75973: Apache Tomcat · Improper Authentication

Affects Apache TomcatSource CVE Database V5

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Not known to be exploited · CVSS 7.3 High.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 3.1 base score

7.3High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Apache Software FoundationApache Tomcat	Affected >=11.0.0-M1 <=11.0.25 >=10.1.0-M1 <=10.1.59 >=9.0.0.M4 <=9.0.121 >=8.5.0 <=8.5.100	Fixed in–
Mavenorg.apache.tomcat/tomcat`pkg:maven/org.apache.tomcat/tomcat`Other threats	Affected >=11.0.0-M1 <=11.0.25 >=10.1.0-M1 <=10.1.59 >=9.0.0.M4 <=9.0.121 >=8.5.0 <=8.5.100	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Users should upgrade affected Apache Tomcat versions to 11.0.26, 10.1.60, or 9.0.122 or later, where the issue is fixed. No other mitigation or temporary workaround is indicated. Applying the official fixes is the recommended remediation.

Description

CVE-2026-75973 is an improper authentication vulnerability in Apache Tomcat affecting multiple versions. When Jakarta Authentication is configured with SimpleAuthConfigProvider as the default provider and multiple web applications use it, the authentication realm from the first web application is incorrectly applied to all others. This can lead to authentication bypass or cross-application authentication issues. The vulnerability affects Apache Tomcat versions from 8.5.0 through 8.5.100, 9.0.0.M4 through 9.0.121, 10.1.0-M1 through 10.1.59, and 11.0.0-M1 through 11.0.25. Fixed versions are 8.5.101, 9.0.122, 10.1.60, and 11.0.26. The CVSS score is 7.3 (high severity).

Impact

The vulnerability can lead to improper authentication where the authentication realm of the first web application is applied to others, potentially allowing unauthorized access or privilege escalation across web applications hosted on the same Tomcat instance. This compromises confidentiality, integrity, and availability to some extent as indicated by the CVSS vector (C:L/I:L/A:L).

Summary

This vulnerability in Apache Tomcat involves improper authentication due to the SimpleAuthConfigProvider being used as the default Jakarta Authentication provider across multiple web applications. The realm from the first authenticated web application is reused for all subsequent web applications, potentially allowing unauthorized access or incorrect authentication contexts. The issue affects multiple major versions of Apache Tomcat, including 8.5.x, 9.0.x, 10.1.x, and 11.0.x up to specified versions. The Apache Software Foundation has released fixed versions 11.0.26, 10.1.60, and 9.0.122 to address this problem.

CWE-287Improper Authentication (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Libraries or Frameworks
Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
V9.2.3 (opens in a new tab)
Attack patterns
Fake the Source of Data (opens in a new tab)
Utilizing REST's Trust in the System Resource to Obtain Sensitive Data (opens in a new tab)
Session Hijacking (opens in a new tab)
Token Impersonation (opens in a new tab)
Upload a Web Shell to a Web Server (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Oct 2026, 23:44 UTC

WeaknessesCWE-287

Technical details

References

Community reviews

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