Is CVE-2013-7331 (Microsoft Internet Explorer Information Disclosure) being exploited in the wild?

Yes. CISA added CVE-2013-7331 to its Known Exploited Vulnerabilities catalogue on 25 May 2022, which it does only when there is reliable evidence of active exploitation. CISA has not linked it to known ransomware campaigns. An information disclosure vulnerability exists in Internet Explorer which allows resources loaded into memory to be queried. Any organisation running the affected product should treat remediation as urgent.

How to Treat CVE-2013-7331 as an Actively Exploited Internet Explorer Issue

For this CVE, the practical question is not whether the flaw exists, but whether your environment can still expose it. Because CISA placed it in KEV, the working assumption should be that exploitation has already happened somewhere and that any exposed Internet Explorer footprint deserves immediate attention. Use the vendor advisory and KEV entry to confirm scope, then remove or contain the browser path if you cannot remediate at once.

Even when a vulnerability is old, it can remain operationally relevant if legacy endpoints, compatibility modes, or unmanaged user systems still open the affected product. NIST National Vulnerability Database is useful for checking the canonical record, but KEV status should drive urgency because it reflects observed abuse rather than theoretical weakness.

The central decision is whether Internet Explorer can still be launched, invoked through enterprise settings, or reached by users who have not fully moved to a supported replacement. Where the browser remains present, treat the issue as an exposure problem as much as a patching problem: reduce use, remove unnecessary access, and confirm that remediation actually changes the reachable attack surface.

What the Vulnerability Means in Practice

The vulnerability is an information disclosure condition in Internet Explorer that allows resources loaded into memory to be queried. That matters because disclosure issues are often used to learn something the attacker should not see, then combine that knowledge with follow-on exploitation, session abuse, or targeted credential theft. The flaw is therefore not just about data leakage in the abstract, but about what exposed memory content can reveal to a local or remote attacker depending on the exploit path.

For validation and triage, it helps to anchor the record to the official vulnerability naming and status sources. CVE Program is the authoritative index for the identifier itself, while CISA Known Exploited Vulnerabilities Catalog is the source that confirms active exploitation pressure and remediation urgency.

Because the disclosed information is tied to browser memory, the operational concern is not only the vulnerability entry but also what adjacent browser data may be exposed on a live system. If users have stored sessions, cached data, or long-lived browser state in the affected environment, the consequence can extend beyond a single page view or single workstation.

What to Do When You Cannot Patch Immediately

If patching or removal must wait, reduce exposure first. Disable or restrict Internet Explorer where possible, limit who can launch it, and prevent it from being used for general browsing or untrusted content. If the browser remains necessary for a legacy line-of-business function, isolate that use as tightly as possible and document the exception.

Vulnerability Management Guide is the right internal reference point for turning KEV status into prioritisation, exception handling, and verification. Pair that with Zero-Day and Exploited Vulnerabilities Guide for the operating model around emergency mitigation, compromise assessment, and post-fix validation.

Where the browser is used to access internal portals or administrative tools, the practical response should also include session review and credential hygiene. If an exposure path could reveal authenticated browser state or memory-resident secrets, rotate the material most likely to have been exposed and invalidate active sessions that depended on the affected device or browser instance.

Risk and Threat Considerations

Actively exploited browser flaws matter because they can be used as an entry point or as a supporting step in a larger compromise. Information disclosure often helps an attacker map the environment, weaken defensive assumptions, or harvest data that improves the success of later exploitation.

Failure mechanism: The browser exposes memory-resident resources that should not be queryable, which can leak data that supports follow-on abuse, session compromise, or targeted exploitation.

Impact: Organisations can face unauthorised disclosure, higher likelihood of successful compromise on exposed endpoints, and faster attacker progression when the vulnerable browser remains reachable.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

CIS Controls v8, NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.

Framework	Control / Reference	Relevance
CIS Controls v8	CIS-7 — Continuous Vulnerability Management	KEV-listed flaws need prioritised scanning and remediation.
Recommendation — Prioritise and remediate KEV-listed exposure in the normal vulnerability workflow.
NIST SP 800-53 Rev 5	RA-5 — Vulnerability Monitoring and Scanning	The question is about an exploited vulnerability and exposure verification.
	SI-2 — Flaw Remediation	Actively exploited flaws require timely corrective action and verification.
Recommendation — Monitor for the vulnerable browser footprint and track remediation status until removed. Apply the fix or compensating control and confirm the vulnerable component is no longer reachable.
NIST CSF 2.0	RS.MA-2 — Mitigation	CVE exploitation calls for prompt containment and remediation actions.
Recommendation — Contain the vulnerable exposure and execute the remediation plan without delay.
ISO/IEC 27001:2022	A.8.8 — Management of technical vulnerabilities	This is a technical vulnerability that needs structured handling and remediation.
Recommendation — Track, prioritise, and remediate the vulnerability under formal vulnerability management.

Practitioner Guidance

What to verify: Confirm whether Internet Explorer is still installed, still callable through compatibility settings, or still required by any business workflow. If it is, verify which users, endpoints, and network zones can reach it and whether that access is genuinely necessary.

Decision rule: If the browser is still usable on a production endpoint, treat the issue as an exposure reduction problem first, then a patching problem. If you cannot remove it immediately, constrain its use, isolate its reach, and shorten the time between exposure discovery and remediation confirmation.

Practitioner takeaway: KEV inclusion means you should assume real-world abuse is already plausible, so the right response is to verify exposure, remove unnecessary browser use, and validate that remediation actually closes the path.