How severe is CVE-2018-12243?

CVE-2018-12243 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-12243 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12243?

CVE-2018-12243 affects Symantec Messaging Gateway. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-12243?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-12243 published?

CVE-2018-12243 was published on 2018-09-19 and last updated on 2026-06-17.

CVE-2018-12243

CVE-2018-12243 is a high-severity vulnerability in Symantec Messaging Gateway with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-611.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 5.8
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-611
Affected product: Symantec Messaging Gateway
Published: 2018-09-19
Last modified: 2026-06-17

Description

The Symantec Messaging Gateway product prior to 10.6.6 may be susceptible to a XML external entity (XXE) exploit, which is a type of issue where XML input containing a reference to an external entity is processed by a weakly configured XML parser. The attack uses file URI schemes or relative paths in the system identifier to access files that should not normally be accessible.

Frequently asked questions

What is CVE-2018-12243?: The Symantec Messaging Gateway product prior to 10.6.6 may be susceptible to a XML external entity (XXE) exploit, which is a type of issue where XML input containing a reference to an external entity is processed by a weakly configured XML parser. The attack uses file URI schemes or relative paths in the system identifier to access files that should not normally be accessible.
How severe is CVE-2018-12243?: CVE-2018-12243 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-12243 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12243?: CVE-2018-12243 affects Symantec Messaging Gateway. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-12243?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-12243 published?: CVE-2018-12243 was published on 2018-09-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:symantec:messaging_gateway:*:*:*:*:*:*:*:*

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Other CWE-611 (Improper Restriction of XML External Entity Reference (XXE)) vulnerabilities

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CVE-2018-1000837 — Critical (CVSS 10.0): UML Designer version <= 8.0.0 contains a XML External Entity (XXE) vulnerability in XML parser for plugins that can…
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