How severe is CVE-2015-6291?

CVE-2015-6291 has a CVSS 2.0 base score of 7.8, rated high severity.

Is CVE-2015-6291 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-6291?

CVE-2015-6291 primarily affects Cisco Email Security Appliance. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-6291?

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-2015-6291 published?

CVE-2015-6291 was published on 2015-11-06 and last updated on 2026-06-17.

CVE-2015-6291

CVE-2015-6291 is a high-severity vulnerability in Cisco Email Security Appliance with a CVSS 2.0 base score of 7.8. 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-20.

Key facts

Severity: High (CVSS 2.0 base score 7.8)
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Email Security Appliance
Published: 2015-11-06
Last modified: 2026-06-17

Description

Cisco AsyncOS before 8.5.7-043, 9.x before 9.1.1-023, and 9.5.x and 9.6.x before 9.6.0-046 on Email Security Appliance (ESA) devices mishandles malformed fields during body-contains, attachment-contains, every-attachment-contains, attachment-binary-contains, dictionary-match, and attachment-dictionary-match filtering, which allows remote attackers to cause a denial of service (memory consumption) via a crafted attachment in an e-mail message, aka Bug ID CSCuv47151.

Frequently asked questions

What is CVE-2015-6291?: Cisco AsyncOS before 8.5.7-043, 9.x before 9.1.1-023, and 9.5.x and 9.6.x before 9.6.0-046 on Email Security Appliance (ESA) devices mishandles malformed fields during body-contains, attachment-contains, every-attachment-contains, attachment-binary-contains, dictionary-match, and attachment-dictionary-match filtering, which allows remote attackers to cause a denial of service (memory consumption) via a crafted attachment in an e-mail message, aka Bug ID CSCuv47151.
How severe is CVE-2015-6291?: CVE-2015-6291 has a CVSS 2.0 base score of 7.8, rated high severity.
Is CVE-2015-6291 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-6291?: CVE-2015-6291 primarily affects Cisco Email Security Appliance. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-6291?: 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-2015-6291 published?: CVE-2015-6291 was published on 2015-11-06 and last updated on 2026-06-17.

References

Affected products (16)

cpe:2.3:a:cisco:email_security_appliance:7.7.0-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:7.7.1-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.0_base:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.6-052:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.6-073:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.6-074:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.6-106:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.6-113:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5.7-042:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:8.5_base:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.0.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.0.0-212:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.0.0-461:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.0.5-000:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.1.0-032:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:9.6.0-042:*:*:*:*:*:*:*

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