VulnerabilityPublished 20 Mar 2026Updated 25 Mar 2026

CVE-2026-33013: micronaut-core · Infinite Loop

Affects micronaut-coreSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High : upgrade to 4.10.16 or 3.10.5 soon.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 4.0 base score

8.2High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.10.16, 3.10.5

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; 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 Vulnerable System (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).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Mar 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 1 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

Upgrade micronaut-core and io.micronaut/micronaut-core to 4.10.16 or 3.10.5.

Affected software

Product	Affected	Fixed in
micronaut-projectsmicronaut-core	Affected >=4.0.0-M1 <4.10.16	Fixed in 4.10.16
micronaut-projectsmicronaut-core	Affected <3.10.5	Fixed in 3.10.5
Mavenio.micronaut/micronaut-core`pkg:maven/io.micronaut/micronaut-core`Other threats	Affected <3.10.5 <4.10.16	Fixed in 3.10.5 4.10.16

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

AI-suggested

Upgrade all affected Micronaut Framework instances to version 4.10.16 or later, or 3.10.5 or later, where the vulnerability is fixed.
Implement input validation to detect and reject malformed or suspicious indexed form parameters that could trigger the infinite loop.
Apply rate limiting and request throttling on endpoints accepting form-urlencoded data to reduce the risk of resource exhaustion from repeated exploit attempts.
Monitor application logs and performance metrics for unusual CPU or memory usage spikes indicative of attempted exploitation.
Use Web Application Firewalls (WAFs) with custom rules to block or alert on suspicious form parameter patterns resembling the exploit vector.
Conduct code reviews and testing for similar array index handling issues in custom data binding logic.
Employ runtime application self-protection (RASP) tools to detect and mitigate infinite loop conditions dynamically.
Ensure robust incident response plans are in place to quickly isolate and remediate affected services if exploitation is detected. These measures combined will reduce the attack surface and mitigate the risk of denial of service caused by this vulnerability.

Description

Micronaut Framework is a JVM-based full stack Java framework designed for building modular, easily testable JVM applications. Versions prior to both 4.10.16 and 3.10.5 do not correctly handle descending array index order during form-urlencoded body binding in theJsonBeanPropertyBinder::expandArrayToThreshold, which allows remote attackers to cause a DoS (non-terminating loop, CPU exhaustion, and OutOfMemoryError) via crafted indexed form parameters (e.g., authors[1].name followed by authors[0].name). This issue has been fixed in versions 4.10.16 and 3.10.5.

Impact

The primary impact of CVE-2026-33013 is denial of service due to infinite looping and resource exhaustion. Exploitation can cause affected Micronaut-based applications to consume excessive CPU and memory resources, leading to application crashes or unresponsiveness. This disrupts service availability, potentially affecting business operations, customer experience, and critical backend processes. Since the vulnerability is remotely exploitable without authentication or user interaction, attackers can launch DoS attacks at scale, targeting public-facing APIs or services. Organizations relying on Micronaut for microservices, web applications, or APIs are at risk of service outages. The impact extends to cloud environments, containerized deployments, and enterprise JVM applications using vulnerable Micronaut versions. While confidentiality and integrity are not directly affected, the availability impact can have cascading effects on dependent systems and services. The lack of known exploits in the wild currently limits immediate risk, but the ease of exploitation and high severity score warrant urgent remediation to prevent future attacks.

Summary

CVE-2026-33013 is a vulnerability in the Micronaut Framework's core library (micronaut-core) affecting versions >=4.0.0-M1 and <4.10.16, and all versions below 3.10.5. The root cause is a logic flaw in theJsonBeanPropertyBinder::expandArrayToThreshold method, which incorrectly handles descending array index orders during the binding of form-urlencoded request bodies. Specifically, when processing indexed form parameters such as authors[1].name followed by authors[0].name, the method enters a non-terminating loop due to an unreachable exit condition. This infinite loop causes excessive CPU consumption and eventually triggers an OutOfMemoryError, resulting in a denial of service (DoS) condition. The vulnerability is remotely exploitable without authentication or user interaction, making it a critical availability risk for any JVM applications using the affected Micronaut versions. The flaw is categorized under CWE-835 (Loop with Unreachable Exit Condition). Although no known exploits are currently reported in the wild, the vulnerability's nature and high CVSS score (8.2) indicate a strong potential for exploitation. The issue has been addressed in Micronaut versions 4.10.16 and 3.10.5, where the array index handling logic was corrected to prevent infinite looping. This vulnerability primarily impacts backend services and APIs that rely on Micronaut for HTTP request processing and data binding, especially those accepting form-urlencoded data with complex array parameters.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Mar 2026, 18:49 UTC

WeaknessesCWE-835

Technical details

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