How severe is CVE-2011-2883?

CVE-2011-2883 has a CVSS 2.0 base score of 9.3, rated critical severity.

Is CVE-2011-2883 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2011-2883?

CVE-2011-2883 primarily affects Citrix Access Gateway. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2011-2883?

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

When was CVE-2011-2883 published?

CVE-2011-2883 was published on 2011-07-21 and last updated on 2026-06-16.

CVE-2011-2883

CVE-2011-2883 is a critical-severity vulnerability in Citrix Access Gateway with a CVSS 2.0 base score of 9.3. 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-20.

Key facts

Severity: Critical (CVSS 2.0 base score 9.3)
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Citrix Access Gateway
Published: 2011-07-21
Last modified: 2026-06-16

Description

The NSEPA.NsepaCtrl.1 ActiveX control in nsepa.ocx in Citrix Access Gateway Enterprise Edition 8.1 before 8.1-67.7, 9.0 before 9.0-70.5, and 9.1 before 9.1-96.4 attempts to validate signed DLLs by checking the certificate subject, not the signature, which allows man-in-the-middle attackers to execute arbitrary code via HTTP header data referencing a DLL that was signed with a crafted certificate.

Frequently asked questions

What is CVE-2011-2883?: The NSEPA.NsepaCtrl.1 ActiveX control in nsepa.ocx in Citrix Access Gateway Enterprise Edition 8.1 before 8.1-67.7, 9.0 before 9.0-70.5, and 9.1 before 9.1-96.4 attempts to validate signed DLLs by checking the certificate subject, not the signature, which allows man-in-the-middle attackers to execute arbitrary code via HTTP header data referencing a DLL that was signed with a crafted certificate.
How severe is CVE-2011-2883?: CVE-2011-2883 has a CVSS 2.0 base score of 9.3, rated critical severity.
Is CVE-2011-2883 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2011-2883?: CVE-2011-2883 primarily affects Citrix Access Gateway. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2011-2883?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2011-2883 published?: CVE-2011-2883 was published on 2011-07-21 and last updated on 2026-06-16.

References

http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=928

Affected products (3)

cpe:2.3:a:citrix:access_gateway:8.1:*:enterprise:*:*:*:*:*
cpe:2.3:a:citrix:access_gateway:9.0:*:enterprise:*:*:*:*:*
cpe:2.3:a:citrix:access_gateway:9.1:*:enterprise:*:*:*:*:*

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