CWE-911: Improper Update of Reference Count

BaseIncompleteExploit Likelihood: Medium

The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count.

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Extended Description

Reference counts can be used when tracking how many objects contain a reference to a particular resource, such as in memory management or garbage collection. When the reference count reaches zero, the resource can be de-allocated or reused because there are no more objects that use it. If the reference count accidentally reaches zero, then the resource might be released too soon, even though it is still in use. If all objects no longer use the resource, but the reference count is not zero, then the resource might not ever be released.

Technical Details

Structure
Simple
Vulnerability Mapping
ALLOWED

Applicable To

Languages
CC++Not Language-Specific
Platforms

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-911 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-911, Improper Update of Reference Count, throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Make elimination of CWE-911 a product outcome

Apply CISA's Secure by Design principle of taking ownership of customer security outcomes to CWE-911, Improper Update of Reference Count. Put the weakness in the product threat model and security roadmap, fund class-level design and platform changes, prefer safe defaults and reusable guardrails, and publish measurable progress. Do not transfer the primary burden to customer configuration when the manufacturer can remove or contain the root cause in the product.

Shifting the Balance of Cybersecurity Risk: Secure by Design Software — Cybersecurity and Infrastructure Security Agency

Connect Improper Update of Reference Count to documented attack evidence

Recorded impacts include DoS: Resource Consumption (Memory), DoS: Resource Consumption (Other), and DoS: Crash, Exit, or Restart; observed examples include CVE-2002-0574, CVE-2004-0114, and CVE-2006-3741; related weaknesses include CWE-664, CWE-672, and CWE-772. Use these source-defined anchors to turn CWE-911 into implementation, review, and verification checks for the affected component.

CWE-911: Improper Update of Reference Count — MITRE CWE

Apply precise root-cause mapping to CWE-911

Apply MITRE's full root-cause mapping guidance when using CWE-911, Improper Update of Reference Count. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-911 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-911, Improper Update of Reference Count. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-911: Improper Update of Reference Count?+

CWE-911: Improper Update of Reference Count is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count. Reference counts can be used when tracking how many objects contain a reference to a particular resource, such as in memory management or garbage collection. When the reference count reaches zero, the resource can be de-allocated or reused because there are no more objects that use it. If the reference count accidentally reaches zero, then the resource might be released too soon, even though it is still in use. If all objects no longer use the resource, but the reference count is not zero, then the resource might not ever be released.

What are the security consequences of Improper Update of Reference Count?+

If exploited, CWE-911 (Improper Update of Reference Count) it can compromise Availability, leading to outcomes such as DoS: Resource Consumption (Memory), DoS: Resource Consumption (Other) and DoS: Crash, Exit, or Restart.

Which programming languages are affected by Improper Update of Reference Count?+

CWE-911 commonly affects C, C++ and Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Improper Update of Reference Count?+

MITRE documents real CVEs mapped to CWE-911, including CVE-2002-0574, CVE-2004-0114, CVE-2006-3741, CVE-2007-1383 and CVE-2007-1700. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-911 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

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