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Access GatewayApplication · Citrix

CVE-2011-2882

HIGH · 9.3 CVSS v2.0 Published 2011-07-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Stack-based buffer overflow in 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 allows remote attackers to execute arbitrary code via crafted HTTP header data.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Stack-based buffer overflow in the NSEPA.NsepaCtrl.1 ActiveX control (nsepa.ocx) in Citrix Access Gateway Enterprise Edition allows remote attackers to execute arbitrary code via crafted HTTP header data. The vulnerability affects versions 8.1 before 8.1-67.7, 9.0 before 9.0-70.5, and 9.1 before 9.1-96.4.

MitigationApply the vendor patches (8.1-67.7, 9.0-70.5, or 9.1-96.4 or later) to the affected Citrix Access Gateway installations. If patching is not immediately feasible, disable the vulnerable ActiveX control or restrict access to the affected endpoints.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Access GatewayApplication
Affected:= 8.1= 9.0= 9.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Citrix Access Gateway installation
    Check system for presence of Citrix Access Gateway software by looking for installation directories, services, or the nsepa.ocx ActiveX control file on the system.
    Affected if Citrix Access Gateway Enterprise Edition is installed and the nsepa.ocx file is present on the system.
  2. Determine installed version
    Query the installed Citrix Access Gateway version through installed programs list, product information, or version file if available. Compare the version number against the affected ranges: 8.1 before 8.1-67.7, 9.0 before 9.0-70.5, or 9.1 before 9.1-96.4.
    Affected if The installed version is 8.1, 9.0, or 9.1 and is lower than the patched versions (8.1-67.7, 9.0-70.5, or 9.1-96.4).
  3. Locate the vulnerable ActiveX control
    Search for the nsepa.ocx file on the system, typically found in the Citrix Access Gateway installation directory or Windows system directories.
    Affected if The nsepa.ocx file exists on the system.
  4. Check if NSEPA ActiveX control is registered
    Inspect Windows registry for the presence of the NSEPA.NsepaCtrl.1 CLSID registration under HKLM\SOFTWARE\Classes\ or verify the control is loadable by browsers or dependent applications.
    Affected if The NSEPA.NsepaCtrl.1 ActiveX control is registered and accessible.

The system is affected if Citrix Access Gateway Enterprise Edition versions 8.1, 9.0, or 9.1 are installed with the nsepa.ocx ActiveX control present and the version is below the patched releases (8.1-67.7, 9.0-70.5, or 9.1-96.4).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor patches (8.1-67.7, 9.0-70.5, or 9.1-96.4 or later) to the affected Citrix Access Gateway installations. If patching is not immediately feasible, disable the vulnerable ActiveX control or restrict access to the affected endpoints.

Recommended fix High confidence

Access Gateway 8.1-67.7, 9.0-70.5, or 9.1-96.4 (depending on your baseline version)

  1. 1. Identify the currently installed Citrix Access Gateway version (8.1, 9.0, or 9.1)
  2. 2. Download the appropriate cumulative hotfix from Citrix support based on your current version
  3. 3. For Access Gateway 8.1: Apply hotfix 8.1-67.7 or later
  4. 4. For Access Gateway 9.0: Apply hotfix 9.0-70.5 or later
  5. 5. For Access Gateway 9.1: Apply hotfix 9.1-96.4 or later
  6. 6. Restart the Access Gateway services as required by the hotfix installation
  7. 7. Verify the installed version matches or exceeds the security fix level

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Access Gateway Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2011-2882 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data