CVE-2026-33036 Vulnerability Analysis & Exploit Details

CVE-2026-33036
Vulnerability Scoring

7.5
/10
Very High Risk

Highly exploitable, CVE-2026-33036 poses a critical security risk that could lead to severe breaches.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-33036 Details

Status: Analyzed

Last updated: 🕓 23 Mar 2026, 16:28 UTC
Originally published on: 🕕 20 Mar 2026, 06:16 UTC

Time between publication and last update: 3 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2026-33036 Vulnerability Summary

CVE-2026-33036: fast-xml-parser allows users to process XML from JS object without C/C++ based libraries or callbacks. Versions 4.0.0-beta.3 through 5.5.5 contain a bypass vulnerability where numeric character references (&#NNN;, &#xHH;) and standard XML entities completely evade the entity expansion limits (e.g., maxTotalExpansions, maxExpandedLength) added to fix CVE-2026-26278, enabling XML entity expansion Denial of Service. The root cause is that replaceEntitiesValue() in OrderedObjParser.js only enforces expansion counting on DOCTYPE-defined entities while the lastEntities loop handling numeric/standard entities performs no counting at all. An attacker supplying 1M numeric entity references like A can force ~147MB of memory allocation and heavy CPU usage, potentially crashing the process—even when developers have configured strict limits. This issue has been fixed in version 5.5.6.

Assessing the Risk of CVE-2026-33036

Access Complexity Graph

The exploitability of CVE-2026-33036 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-33036

With low attack complexity and no required privileges, CVE-2026-33036 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-33036, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-33036, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-33036 has no significant impact on data confidentiality.
  • Integrity: None
    CVE-2026-33036 poses no threat to data integrity.
  • Availability: High
    CVE-2026-33036 can disrupt system operations, potentially causing complete denial of service (DoS).

CVE-2026-33036 References

External References

CWE Common Weakness Enumeration

CWE-776

CAPEC Common Attack Pattern Enumeration and Classification

  • Exponential Data Expansion CAPEC-197 An adversary submits data to a target application which contains nested exponential data expansion to produce excessively large output. Many data format languages allow the definition of macro-like structures that can be used to simplify the creation of complex structures. However, this capability can be abused to create excessive demands on a processor's CPU and memory. A small number of nested expansions can result in an exponential growth in demands on memory.

Vulnerable Configurations

  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.6:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.7:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.7:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.8:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.8:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.9:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.9:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.10:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.10:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.11:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.11:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.12:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.12:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.13:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.13:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.14:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.14:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.15:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.15:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.1.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.6:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.6:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.7:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.2.7:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.6:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.3.6:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.4.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.4.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.5.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.6:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.7:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.7:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.8:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.8:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.9:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.0.9:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.2.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.1:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.1:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.2:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.2:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.3:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.3:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.4:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.4:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.5:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.5:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.6:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.6:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.7:*:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:5.3.7:*:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:-:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:-:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta3:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta3:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta4:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta4:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta5:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta5:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta6:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta6:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta7:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta7:*:*:*:*:*:*
  • cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta8:*:*:*:*:*:*
    cpe:2.3:a:naturalintelligence:fast-xml-parser:4.0.0:beta8:*:*:*:*:*:*

Protect Your Infrastructure against CVE-2026-33036: Combat Critical CVE Threats

Stay updated with real-time CVE vulnerabilities and take action to secure your systems. Enhance your cybersecurity posture with the latest threat intelligence and mitigation techniques. Develop the skills necessary to defend against CVEs and secure critical infrastructures. Join the top cybersecurity professionals safeguarding today's infrastructures.

Other 5 Recently Published CVEs Vulnerabilities

  • CVE-2026-4867 – Impact: A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is n...
  • CVE-2026-3116 – Mattermost Plugins versions <=11.4 11.0.4 11.1.3 11.3.2 10.11.11.0 fail to validate incoming request size which allows an authenticated attacker to...
  • CVE-2026-3115 – Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group...
  • CVE-2026-3114 – Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to validate decompressed archive entry sizes dur...
  • CVE-2026-3113 – Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to set permissions on downloaded bulk export whi...