xmltodict's unparse function delegates element-name handling to Python's xml.sax.saxutils.XMLGenerator, which performs no validation of element names. This flaw lets attackers inject crafted XML that can manipulate the output of unparse, potentially altering the structure or contents of data processed by downstream consumers. The issue is identified as CWE‑91 and can lead to data corruption or unintended data processing. The vulnerability is reported in versions 0.14.2 through just before 0.15.1.

The vulnerability affects the xmltodict library across all supported operating systems—Linux, macOS, and Windows—for every release from 0.14.2 up to the point immediately before 0.15.1. Any application that imports xmltodict and uses the unparse facility in those versions is potentially exposed.

The CVSS score of 6.9 indicates moderate severity. The EPSS score is below 1 %, suggesting a low probability of exploitation in the current environment. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires local access to code that calls xmltodict.unparse; there is no documented network-facing vector. The risk therefore is limited to contexts where an attacker can influence input to the unparse routine, enabling data manipulation.