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Unrated severityNVD Advisory· Published Feb 8, 2021· Updated Aug 3, 2024

CVE-2021-26221

CVE-2021-26221

Description

The ezxml_new function in ezXML 0.8.6 and earlier is vulnerable to OOB write when opening XML file after exhausting the memory pool.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

ezXML 0.8.6 and earlier has an out-of-bounds write in ezxml_new when memory pool exhaustion causes incorrect error handling of calloc.

Vulnerability

The ezxml_new function in ezXML versions 0.8.6 and earlier is vulnerable to an out-of-bounds write when opening an XML file after exhausting the memory pool. The root cause lies in incorrect error handling of the return value from calloc (or malloc) in ezxml.c line 838. When memory allocation fails (e.g., due to memory pool exhaustion), the function does not properly check for a NULL return, leading to an OOB write on a near-zero or freed buffer [1].

Exploitation

An attacker can trigger this vulnerability by providing a specially crafted XML file that causes multiple memory allocations to exhaust the heap or memory pool. The exploitation can be local (e.g., when the user opens a malicious file with an application using ezXML) or remote if the application parses XML from an untrusted network source. No authentication is required, but the attacker must be able to deliver the file to the parser. The OOB write can occur during the ezxml_new call, which is invoked while parsing the XML structure [1].

Impact

Successful exploitation can result in an out-of-bounds write, potentially causing a segmentation fault (denial of service) or, in environments with limited memory protection (e.g., embedded systems), a near-NULL pointer overwrite. This could lead to arbitrary code execution or other privilege escalation depending on the memory layout and mitigation controls [1].

Mitigation

As of the publication date (2021-02-08), no official patch was available; the bug report remains open [1]. Users should monitor the ezXML project for an updated version that fixes the memory allocation error handling. In the absence of a patch, avoid parsing untrusted XML files with ezXML 0.8.6 or earlier. The vulnerability is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog at this time.

References
  1. ezXML / Bugs / #21 Out-of-bounds write caused by incorrect error handling of malloc in ezxml_new (ezxml.c:838)

AI Insight generated on May 27, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

59

Patches

0

No patches discovered yet.

Vulnerability mechanics

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References

1

News mentions

0

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