← Vulnerability feed

Vulnerability record · CVE-2011-5124 · published 26 August 2012

CVE-2011-5124: Blue Coat ProxySG BCAAA stack buffer overflow via sync port

Bluecoat · Proxyone

The BCAAA component used by Blue Coat ProxySG 4.2.3 through 6.1 and ProxyOne contains a stack-based buffer overflow that is triggered by a large packet sent to the synchronization port (16102/tcp). Because the flaw is remotely reachable over the network with no authentication, it can lead to arbitrary code execution on the affected appliance.

10.0 CVSS 2.0 High EPSS 55% · top 1.0% CWE-119 · Memory buffer overflow
10.0CVSS 2.0 base score
55%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
16 Jun 2026Last modified by NVD

Description

Stack-based buffer overflow in the BCAAA component before build 60258, as used by Blue Coat ProxySG 4.2.3 through 6.1 and ProxyOne, allows remote attackers to execute arbitrary code via a large packet to the synchronization port (16102/tcp).

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

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: medium.

critical priorityCVSS 2.0 score of 10 with network reachability, no authentication, and full confidentiality, integrity, and availability impact, combined with a very high EPSS percentile, makes this a top remediation priority.

What it is

The BCAAA component used by Blue Coat ProxySG 4.2.3 through 6.1 and ProxyOne contains a stack-based buffer overflow that is triggered by a large packet sent to the synchronization port (16102/tcp). Because the flaw is remotely reachable over the network with no authentication, it can lead to arbitrary code execution on the affected appliance.

Impact

A remote attacker can execute arbitrary code on the ProxySG or ProxyOne appliance, gaining full control of the device and any traffic or credentials it handles.

Attack surface

Reached over the network by sending a crafted large packet to TCP port 16102, the BCAAA synchronization port. The CVSS vector (AV:N/AC:L/Au:N) indicates no authentication and no user interaction are required.

Exploitation

Not listed in CISA KEV and no reference tags indicate known exploitation, but EPSS is 0.54648 (99th percentile), indicating a high modeled likelihood of exploitation activity.

What to do

  • Upgrade BCAAA to build 60258 or later as directed by Blue Coat advisory SA55, and apply the corresponding ProxySG/ProxyOne firmware update.
  • Restrict network access to TCP port 16102 to only trusted BCAAA peers using firewall rules or ACLs.
  • Segment management and synchronization interfaces from untrusted networks and the general internet.
  • Monitor vendor advisories for the affected ProxySG 4.2.3 through 6.1 and ProxyOne platforms and plan replacement if no supported fix exists.

Detection

  • Monitor network traffic to TCP port 16102 for oversized or malformed packets targeting BCAAA synchronization.
  • Alert on unexpected crashes, restarts, or process failures in the BCAAA component on ProxySG and ProxyOne appliances.
  • Review firewall and flow logs for connections to port 16102 from hosts outside the expected BCAAA peer set.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://kb.bluecoat.com/index?page=content&id=SA55
https://kb.bluecoat.com/index?page=content&id=SA55

Track CVE-2011-5124 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.3CVE-2010-5189Bluecoat sgos permissions and access controls vulnerabilityBlue Coat ProxySG before SGOS 4.3.4.1, 5.x before SGOS 5.4.5.1, 5.5 before SGOS 5.5.4.1, and 6.x before SGOS 6.1.1.1 allows remote authenticated user…EPSS 1.8%7.5CVE-2016-6594Bluecoat advanced secure gateway vulnerabilityBlue Coat Advanced Secure Gateway 6.6, CacheFlow 3.4, ProxySG 6.5 and 6.6 allows remote attackers to bypass blocked requests, user authentication, an…EPSS 1.3%7.5CVE-2004-0079Cisco firewall services module null pointer dereference vulnerabilityThe do_change_cipher_spec function in OpenSSL 0.9.6c to 0.9.6k, and 0.9.7a to 0.9.7c, allows remote attackers to cause a denial of service (crash) vi…EPSS 9.5%7.4CVE-2015-8597Bluecoat proxysg vulnerabilityOpen redirect vulnerability in Blue Coat ProxySG 6.5 before 6.5.8.8 and 6.6 and Advanced Secure Gateway (ASG) 6.6 might allow remote attackers to red…EPSS 1.9%7.1CVE-2013-5959Bluecoat proxysgos memory buffer overflow vulnerabilityBlue Coat ProxySG before 6.2.14.1, 6.3.x, 6.4.x, and 6.5 before 6.5.2 allows remote attackers to cause a denial of service (memory consumption and dr…EPSS 1.5%5.8CVE-2009-1211Bluecoat proxysg va-10 vulnerabilityBlue Coat ProxySG, when transparent interception mode is enabled, uses the HTTP Host header to determine the remote endpoint, which allows remote att…EPSS 1.4%5.0CVE-2010-5190Bluecoat sgos permissions and access controls vulnerabilityThe Active Content Transformation functionality in Blue Coat ProxySG before SGOS 4.3.4.2, 5.x before SGOS 5.4.5.1, 5.5 before SGOS 5.5.4.1, and 6.x b…EPSS 1.4%5.0CVE-2004-0081Cisco firewall services module vulnerabilityOpenSSL 0.9.6 before 0.9.6d does not properly handle unknown message types, which allows remote attackers to cause a denial of service (infinite loop…EPSS 7.2%

Source: NIST National Vulnerability Database (record CVE-2011-5124), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.