CVE-2011-5124: Stack-based buffer overflow in the BCAAA component before build 60258, as used by Blue Coat ProxySG 4.2.3 thro

This week

HIGH 10.0MITIGATEDOWNGRADEMITIGATE

CVE-2011-5124 is a high-severity flaw (CVSS 10.0) affecting proxyone, proxysg, proxysg. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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).

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	54.6% (top 1%)
CISA exploited list	No
Weakness	CWE-119
Published	2012-08-26
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: bluecoat

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2012-08-26 19:55 UTCPublished CVE record published
2026-06-16 23:35 UTCUpdated Record last modified

bluecoat proxyone MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy proxyone || rpm -q proxyone || proxyone --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

bluecoat proxysg DOWNGRADE

Affected: 4.2.6 · 4.3.2.3 · 5.1 · 5.1.6.1 · 5.2 · 5.2.2.4 · 5.2.5.2 · 5.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.2.6

1. Check installed version

apt-cache policy proxysg || rpm -q proxysg || proxysg --version

2. No fixed release: DOWNGRADE to a release before 4.2.6 (Debian / Ubuntu)

apt-cache madison proxysg sudo apt install proxysg=<VERSION_BEFORE_4.2.6> sudo apt-mark hold proxysg

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list proxysg sudo dnf downgrade proxysg-<VERSION_BEFORE_4.2.6> sudo dnf versionlock add proxysg

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

bluecoat proxysg MITIGATE

Affected: 6

Fixed in: no fixed release known

Safe to downgrade to: a release before 6

Firmware

Install the latest firmware from the vendor advisory; if none, apply the vendor workaround.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Blue Coat Authentication and Authorization Agent (BCAAA) 5 - Remote Buffer Overflow (Metasploit)
Metasploit: Blue Coat Authentication and Authorization Agent (BCAAA) 5 Buffer Overflow

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2011-5124?

proxyone: mitigate or apply the listed mitigation; proxysg: downgrade or apply the listed mitigation; proxysg: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2011-5124 being exploited?

CVE-2011-5124 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2011-5124 affect?

CVE-2011-5124 affects proxyone, proxysg, proxysg. Severity is high (CVSS 10.0). 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)

How urgent is CVE-2011-5124?

Priority 65/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference

References

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