How severe is CVE-2011-4661?

CVE-2011-4661 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2011-4661 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-4661?

CVE-2011-4661 affects Cisco Ios. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2011-4661?

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-2011-4661 published?

CVE-2011-4661 was published on 2020-02-12 and last updated on 2026-06-16.

CVE-2011-4661

CVE-2011-4661 is a high-severity vulnerability in Cisco Ios with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-772.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-772
Affected product: Cisco Ios
Published: 2020-02-12
Last modified: 2026-06-16

Description

A memory leak vulnerability exists in Cisco IOS before 15.2(1)T due to a memory leak in the HTTP PROXY Server process (aka CSCtu52820), when configured with Cisco ISR Web Security with Cisco ScanSafe and User Authenticaiton NTLM configured.

Frequently asked questions

What is CVE-2011-4661?: A memory leak vulnerability exists in Cisco IOS before 15.2(1)T due to a memory leak in the HTTP PROXY Server process (aka CSCtu52820), when configured with Cisco ISR Web Security with Cisco ScanSafe and User Authenticaiton NTLM configured.
How severe is CVE-2011-4661?: CVE-2011-4661 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2011-4661 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-4661?: CVE-2011-4661 affects Cisco Ios. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2011-4661?: 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-2011-4661 published?: CVE-2011-4661 was published on 2020-02-12 and last updated on 2026-06-16.

References

https://www.cisco.com/c/en/us/td/docs/ios/15_2m_and_t/release/notes/15_2m_and_t/152-1TCAVS.html

Affected products (1)

cpe:2.3:o:cisco:ios:*:*:*:*:*:*:*:*

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