CVE-2025-53506VulnerabilityPublished 10 Jul 2025Updated 4 Nov 2025

CVE-2025-53506: Apache Tomcat · Uncontrolled Resource Consumption

Affects Apache TomcatSource CVE Database V5

Not known to be exploited · CVSS 7.5 High · fixed in 11.0.9 : patch Apache Tomcat soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 2.1% chance of exploitation in 30 days – higher than 81% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 11.0.9

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-25.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC 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
Mavenorg.apache.tomcat/tomcat`pkg:maven/org.apache.tomcat/tomcat`Other threats	Affected =11.0.0-M1 <=11.0.8 =11.0.0-M1	Fixed in–

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

AI-suggested

To mitigate CVE-2025-53506, organizations should immediately upgrade Apache Tomcat to the fixed versions 11.0.9, 10.1.43, or 9.0.107 depending on their current deployment. If immediate upgrade is not feasible, administrators should consider temporarily disabling HTTP/2 support to prevent exploitation, though this may impact performance. Network-level mitigations such as rate limiting and connection throttling on HTTP/2 traffic can reduce the risk of resource exhaustion. Monitoring server resource usage and HTTP/2 connection metrics can help detect anomalous activity indicative of exploitation attempts. Implementing Web Application Firewalls (WAFs) with HTTP/2 anomaly detection capabilities may provide additional protection. Regularly reviewing and updating incident response plans to include DoS scenarios related to HTTP/2 is recommended. Finally, organizations should maintain an inventory of Tomcat versions in use and ensure timely patch management processes are in place to address future vulnerabilities.

Description

Uncontrolled Resource Consumption vulnerability in Apache Tomcat if an HTTP/2 client did not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.8, from 10.1.0-M1 through 10.1.42, from 9.0.0.M1 through 9.0.106. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Other EOL versions may also be affected. Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.

Impact

The primary impact of CVE-2025-53506 is on the availability of web services hosted on Apache Tomcat servers. An attacker can exploit this vulnerability to cause a denial-of-service by exhausting server resources through uncontrolled concurrent HTTP/2 streams. For European organizations, this can disrupt critical business applications, customer-facing portals, and internal services that rely on Tomcat, leading to operational downtime and potential financial losses. Sectors such as finance, government, healthcare, and e-commerce, which often use Tomcat for their web infrastructure, are particularly vulnerable. Additionally, prolonged service outages can damage organizational reputation and erode customer trust. Since the vulnerability requires no authentication or user interaction, it can be exploited by remote attackers with minimal effort, increasing the threat landscape. The lack of confidentiality or integrity impact means data breaches are unlikely, but service disruption alone can have severe consequences, especially for time-sensitive or critical services.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (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 5 Nov 2025, 15:48 UTC

WeaknessesCWE-400

Technical details

References

Community reviews

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