CVE-2009-0636

CVE-2009-0636 is a high-severity vulnerability in Cisco Ios with a CVSS 2.0 base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

• Severity: High (CVSS 2.0 base score 7.8)
• EPSS exploit prediction: 3% (85th percentile)
• Actively exploited: Not listed in CISA KEV
• Affected product: Cisco Ios
• Published: 2009-03-27
• Last modified: 2026-06-16

Description

Unspecified vulnerability in Cisco IOS 12.0 through 12.4, when SIP voice services are enabled, allows remote attackers to cause a denial of service (device crash) via a valid SIP message.

Frequently asked questions

What is CVE-2009-0636?

Unspecified vulnerability in Cisco IOS 12.0 through 12.4, when SIP voice services are enabled, allows remote attackers to cause a denial of service (device crash) via a valid SIP message.

How severe is CVE-2009-0636?

CVE-2009-0636 has a CVSS 2.0 base score of 7.8, rated high severity.

Is CVE-2009-0636 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-0636?

CVE-2009-0636 primarily affects Cisco Ios. In total, 310 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2009-0636?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2009-0636 published?

CVE-2009-0636 was published on 2009-03-27 and last updated on 2026-06-16.

References

• http://secunia.com/advisories/34438
• http://securitytracker.com/id?1021902
• http://www.cisco.com/en/US/products/products_security_advisory09186a0080a90469.shtml
• http://www.cisco.com/en/US/products/products_security_advisory09186a0080a904c0.shtml
• http://www.securityfocus.com/bid/34243
• http://www.vupen.com/english/advisories/2009/0851
• https://exchange.xforce.ibmcloud.com/vulnerabilities/49421

Affected products (310)

• cpe:2.3:o:cisco:ios:12.0:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0da:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0db:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0dc:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0s:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sc:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sl:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sp:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0st:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sx:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sy:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0sz:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0t:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0w:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0wc:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0wt:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0wx:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xa:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xb:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xc:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xd:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xe:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xg:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xh:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xi:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xj:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xk:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xl:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xm:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xn:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xq:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xr:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xs:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xt:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.0xv:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.1:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.1aa:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.1ax:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.1ay:*:*:*:*:*:*:*
• cpe:2.3:o:cisco:ios:12.1az:*:*:*:*:*:*:*

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