CVE-2021-21827: att xmill Classic Buffer Overflow

Vulnerability summary

CVE-2021-21827 is a critical (CVSS 9.8) Classic Buffer Overflow vulnerability in att xmill. EPSS estimates a 1.14% chance of exploitation in the next 30 days, higher than 66% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 20-08-2021
   PublishedVulnerability first disclosed.
2. 03-08-2024
   Last modifiedVulnerability information updated.

Description

A heap-based buffer overflow vulnerability exists in the XML Decompression DecodeTreeBlock functionality of AT&T Labs Xmill 0.7. Within `DecodeTreeBlock` which is called during the decompression of an XMI file, a UINT32 is loaded from the file and used as trusted input as the length of a buffer. An attacker can provide a malicious file to trigger this vulnerability.

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.