2021-21827 | AT&T Xmill XML Decompression heap-based overflow (TALOS-2021-1291)

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.1	$0-$5k	0.17

A vulnerability was found in AT&T Xmill 0.7. It has been rated as critical. This issue affects an unknown functionality of the component XML Decompression Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-122. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was shared 08/21/2021 as TALOS-2021-1291. It is possible to read the advisory at talosintelligence.com. The identification of this vulnerability is CVE-2021-21827 since 01/04/2021. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/25/2021).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Vendor

Name

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.1

VulDB Base Score: 6.3
VulDB Temp Score: 6.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍
Class: Memory corruption
CWE: CWE-122
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	unlock	unlock	unlock	unlock
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Threat Intelligenceinfoedit

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

01/04/2021 CVE assigned
08/21/2021 +228 days Advisory disclosed
08/21/2021 +0 days VulDB entry created
08/25/2021 +4 days VulDB last updateAdvisory: TALOS-2021-1291
Status: Not defined

CVE: CVE-2021-21827 (🔒)

Created: 08/21/2021 08:28
Updated: 08/25/2021 16:32
Changes: (2) source_cve_assigned source_cve_nvd_summary
Complete: 🔍

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