Microsoft Edge Chakra JIT GlobOpt::OptTagChecks memory corruption

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.
5.8	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as critical has been found in Microsoft Edge. The impacted element is the function GlobOpt::OptTagChecks of the component Chakra JIT. Executing a manipulation can lead to memory corruption. This vulnerability is handled as CVE-2017-11840. The attack can be executed remotely. Additionally, an exploit exists. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability has been found in Microsoft Edge (Web Browser) (the affected version unknown) and classified as critical. This vulnerability affects the function GlobOpt::OptTagChecks of the component Chakra JIT. The manipulation with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability.

The bug was discovered 11/14/2017. The weakness was released 11/14/2017 by lokihardt with Google Project Zero as KB4048956 as confirmed security update guide (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability was named CVE-2017-11840 since 07/31/2017. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. Technical details and also a public exploit are known. The advisory points out:

A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Microsoft Edge. The vulnerability could corrupt memory in such a way that an attacker could execute arbitrary code in the context of the current user. An attacker who successfully exploited the vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited the vulnerability could take control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

A public exploit has been developed by Google Security Research and been published 2 weeks after the advisory. It is possible to download the exploit at exploit-db.com. It is declared as proof-of-concept. As 0-day the estimated underground price was around $25k-$100k. The vulnerability scanner Nessus provides a plugin with the ID 104552 (KB4048956: Windows 10 LTSB November 2017 Cumulative Update), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Windows : Microsoft Bulletins and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 91413 (Microsoft Edge Security Update for November 2017). The code used by the exploit is:

function opt() {
    let obj = [2.3023e-320];
    for (let i = 0; i < 1; i++) {
        obj.x = 1;  // In the first analysis, BailOnNotObject emitted
        obj = +obj;  // Change the type
        obj.x = 1;  // Type confusion
    }
}
 
function main() {
    for (let i = 0; i < 1000; i++) {
        opt();
    }
}

Applying the patch KB4048956 is able to eliminate this problem. The bugfix is ready for download at catalog.update.microsoft.com. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (43183), Tenable (104552) and SecurityFocus (BID 101734†). Entries connected to this vulnerability are available at VDB-109334, VDB-109335, VDB-109337 and VDB-109338. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Web Browser

Vendor

Microsoft

Name

Edge

License

commercial

Website

Vendor: https://www.microsoft.com/

CPE 2.3info

🔍

CPE 2.2info

🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.0
VulDB Meta Temp Score: 5.8

VulDB Base Score: 6.3
VulDB Temp Score: 5.7
VulDB Vector: 🔍
VulDB Reliability: 🔍

Vendor Base Score (Microsoft): 4.2
Vendor Vector (Microsoft): 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Proof-of-Concept
Author: Google Security Research
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 104552
Nessus Name: KB4048956: Windows 10 LTSB November 2017 Cumulative Update
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 880598
OpenVAS Name: Microsoft Windows Multiple Vulnerabilities (KB4048956)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍
Exploit Delay Time: 🔍

Patch: KB4048956

Timelineinfo

07/31/2017 🔍
11/14/2017 +106 days 🔍
11/14/2017 +0 days 🔍
11/14/2017 +0 days 🔍
11/14/2017 +0 days 🔍
11/14/2017 +0 days 🔍
11/14/2017 +0 days 🔍
11/15/2017 +1 days 🔍
11/27/2017 +12 days 🔍
11/27/2017 +0 days 🔍
12/14/2025 +2939 days 🔍

Sourcesinfo

Vendor: microsoft.com

Advisory: KB4048956
Researcher: lokihardt
Organization: Google Project Zero
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-11840 (🔍)
GCVE (CVE): GCVE-0-2017-11840
GCVE (VulDB): GCVE-100-109336

OVAL: 🔍

SecurityFocus: 101734 - Microsoft Edge Scripting Engine CVE-2017-11840 Remote Memory Corruption Vulnerability
SecurityTracker: 1039780

scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 11/15/2017 09:35
Updated: 12/14/2025 18:33
Changes: 11/15/2017 09:35 (97), 12/11/2019 20:51 (7), 01/23/2021 11:30 (3), 12/14/2025 18:33 (15)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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