CVE-2018-5241: Symantec Advanced Secure Gateway (ASG) 6.6 and 6.7, and ProxySG 6.5, 6.6, and 6.7 are susceptible to a SAML au

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CRITICAL 9.8REMOTEDOWNGRADEDOWNGRADE

CVE-2018-5241 is a critical-severity flaw (CVSS 9.8) affecting advanced secure gateway, symantec proxysg. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Symantec Advanced Secure Gateway (ASG) 6.6 and 6.7, and ProxySG 6.5, 6.6, and 6.7 are susceptible to a SAML authentication bypass vulnerability. The products can be configured with a SAML authentication realm to authenticate network users in intercepted proxy traffic. When parsing SAML responses, ASG and ProxySG incorrectly handle XML nodes with comments. A remote attacker can modify a valid SAML response without invalidating its cryptographic si

Why this priority

Critical severity
EPSS top 8%: very likely to be exploited
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	4.5% (top 8%)
CISA exploited list	No
Published	2018-05-29
Last modified	2026-06-17

Publisher (CNA): Symantec Corporation · Vendor: broadcom

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-05-29 13:29 UTCPublished CVE record published
2026-06-17 01:59 UTCUpdated Record last modified

broadcom advanced secure gateway DOWNGRADE

Affected: 6.6 · 6.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.6

1. Check installed version

apt-cache policy advanced-secure-gateway || rpm -q advanced-secure-gateway || advanced-secure-gateway --version

2. No fixed release: DOWNGRADE to a release before 6.6 (Debian / Ubuntu)

apt-cache madison advanced-secure-gateway sudo apt install advanced-secure-gateway=<VERSION_BEFORE_6.6> sudo apt-mark hold advanced-secure-gateway

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

dnf --showduplicates list advanced-secure-gateway sudo dnf downgrade advanced-secure-gateway-<VERSION_BEFORE_6.6> sudo dnf versionlock add advanced-secure-gateway

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.

broadcom symantec proxysg DOWNGRADE

Affected: 6.5 · 6.6 · 6.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.5

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 6.5 (Debian / Ubuntu)

apt-cache madison symantec-proxysg sudo apt install symantec-proxysg=<VERSION_BEFORE_6.5> sudo apt-mark hold symantec-proxysg

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

dnf --showduplicates list symantec-proxysg sudo dnf downgrade symantec-proxysg-<VERSION_BEFORE_6.5> sudo dnf versionlock add symantec-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.

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-2018-5241?

advanced secure gateway: downgrade or apply the listed mitigation; symantec proxysg: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-5241 being exploited?

CVE-2018-5241 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-2018-5241 affect?

CVE-2018-5241 affects advanced secure gateway, symantec proxysg. Severity is critical (CVSS 9.8). Symantec Advanced Secure Gateway (ASG) 6.6 and 6.7, and ProxySG 6.5, 6.6, and 6.7 are susceptible to a SAML authentication bypass vulnerability. The products can be configured with a SAML authentication realm to authenticate network users i

How urgent is CVE-2018-5241?

Priority 62/100. Critical severity; EPSS top 8%: very likely to be exploited; Remotely exploitable, no login, no user action

Software pages

Symantec and Broadcom vulnerabilities

Related CVEs

CVE-2023-23955 HIGH 8.1 UPGRADE UPGRADE Advanced Secure Gateway and Content Analysis, prior to 7.3.13.1 / 3.1.6.0, may be susceptible to a Server-Side
CVE-2023-23954 MEDIUM 5.4 UPGRADE UPGRADE Advanced Secure Gateway and Content Analysis, prior to 7.3.13.1 / 3.1.6.0, may be susceptible to a Stored Cros
CVE-2023-23953 HIGH 7.8 UPGRADE UPGRADE Advanced Secure Gateway and Content Analysis, prior to 7.3.13.1 / 3.1.6.0, may be susceptible to an Elevation
CVE-2023-23952 CRITICAL 9.8 UPGRADE UPGRADE Advanced Secure Gateway and Content Analysis, prior to 7.3.13.1 / 3.1.6.0, may be susceptible to a Command Inj
CVE-2021-46825 CRITICAL 9.1 DOWNGRADE DOWNGRADE Symantec Advanced Secure Gateway (ASG) and ProxySG are susceptible to an HTTP desync vulnerability

References

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