CVE-2010-0806: Microsoft Internet Explorer Use-After-Free Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Microsoft Internet Explorer. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-05-20, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-06-03; treat that as the outer limit, not the target.
• EPSS 82.2%, percentile 99.7: FIRST’s model estimates a 82.2% chance of exploitation activity in the next 30 days, higher than 99.7% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.

What it is

Use-after-free vulnerability in the Peer Objects component (aka iepeers.dll) in Microsoft Internet Explorer 6, 6 SP1, and 7 allows remote attackers to execute arbitrary code via vectors involving access to an invalid pointer after the deletion of an object, as exploited in the wild in March 2010, aka "Uninitialized Memory Corruption Vulnerability."

CISA’s summary

Microsoft Internet Explorer contains an use-after-free vulnerability that could allow remote attackers to execute arbitrary code via vectors involving access to an invalid pointer after the deletion of an object. The impacted product could be end-of-life (EoL) and/or end-of-service (EoS). Users should discontinue product utilization.

Weakness type: CWE-416, CWE-399.

Product: Microsoft Internet Explorer · Assigned by: microsoft · Published: 2010-03-10

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-05-20; federal due date 2026-06-03. Known ransomware use: Unknown.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 82.24% probability of exploitation activity in the next 30 days; percentile 99.7.

Timeline

• 2010-03-10 — CVE record published by microsoft
• 2026-05-20 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-05-21 — CVE record last updated
• 2026-06-03 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. MS10-018 docs.microsoft.com
2. learn.microsoft.com learn.microsoft.com
3. Listed in CISA KEV notes (learn.microsoft.com) learn.microsoft.com

Vulnerability records

1. CVE.org record CVE-2010-0806 cve.org
2. NVD entry CVE-2010-0806 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. 62810 osvdb.org
2. TA10-089A us-cert.gov
3. 38615 securityfocus.com
4. ADV-2010-0567 vupen.com
5. 38860 secunia.com
6. TA10-068A us-cert.gov
7. microsoft.com microsoft.com
8. ms-ie-useafterfree-code-execution(56772) exchange.xforce.ibmcloud.com
9. oval:org.mitre.oval:def:8446 oval.cisecurity.org
10. ADV-2010-0744 vupen.com
11. blogs.technet.com blogs.technet.com
12. VU#744549 kb.cert.org

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