CVE-2013-5959: Blue 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 denia

Q: How do I fix CVE-2013-5959?

proxysgos: downgrade or apply the listed mitigation; proxysg: upgrade to newer than 5.3; proxysgos: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2013-5959 being exploited?

CVE-2013-5959 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2013-5959 affect?

CVE-2013-5959 affects proxysgos, proxysg, proxysgos. Severity is high (CVSS 7.1). Blue 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 dropped connections) via a recursive href in an HTML page, which triggers a large number of H

This month

HIGH 7.1DOWNGRADEUPGRADEMITIGATE

CVE-2013-5959 is a high-severity flaw (CVSS 7.1) affecting proxysgos, proxysg, proxysgos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Blue 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 dropped connections) via a recursive href in an HTML page, which triggers a large number of HTTP RW pipeline pre-fetch requests.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.1 (High)
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Weakness	CWE-119
Published	2013-09-28
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

2013-09-28 19:55 UTCPublished CVE record published
2026-06-16 23:59 UTCUpdated Record last modified

bluecoat proxysgos DOWNGRADE

Affected: 5.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.4

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 5.4 (Debian / Ubuntu)

apt-cache madison proxysgos sudo apt install proxysgos=<VERSION_BEFORE_5.4> sudo apt-mark hold proxysgos

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

dnf --showduplicates list proxysgos sudo dnf downgrade proxysgos-<VERSION_BEFORE_5.4> sudo dnf versionlock add proxysgos

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 UPGRADE

Affected: <= 5.3

Fixed in: newer than 5.3

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

bluecoat proxysgos MITIGATE

Affected: 5.3 · 5.5 · 6.1 · 6.2 · 6.3 · 6.4 · 6.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.3

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2013-5959?

proxysgos: downgrade or apply the listed mitigation; proxysg: upgrade to newer than 5.3; proxysgos: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2013-5959 being exploited?

CVE-2013-5959 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-2013-5959 affect?

CVE-2013-5959 affects proxysgos, proxysg, proxysgos. Severity is high (CVSS 7.1). Blue 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 dropped connections) via a recursive href in an HTML page, which triggers a large number of H

How urgent is CVE-2013-5959?

Priority 44/100. High severity

Related CVEs

CVE-2014-2033 HIGH 7.9 UPGRADE The caching feature in SGOS in Blue Coat ProxySG 5.5 through 5.5.11.3, 6.1 through 6.1.6.3, 6.2 through 6.2.15

References

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