How severe is CVE-2015-4321?

CVE-2015-4321 has a CVSS 2.0 base score of 5.0, rated medium severity.

Is CVE-2015-4321 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-4321?

CVE-2015-4321 primarily affects Cisco Adaptive Security Appliance Software. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2015-4321?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2015-4321 published?

CVE-2015-4321 was published on 2015-08-20 and last updated on 2026-06-17.

CVE-2015-4321

CVE-2015-4321 is a medium-severity vulnerability in Cisco Adaptive Security Appliance Software with a CVSS 2.0 base score of 5.0. 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: Medium (CVSS 2.0 base score 5.0)
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Adaptive Security Appliance Software
Published: 2015-08-20
Last modified: 2026-06-17

Description

The Unicast Reverse Path Forwarding (uRPF) implementation in Cisco Adaptive Security Appliance (ASA) Software 9.3(1.50), 9.3(2.100), 9.3(3), and 9.4(1) mishandles cases where an IP address belongs to an internal interface but is also in the ASA routing table, which allows remote attackers to bypass uRPF validation via spoofed packets, aka Bug ID CSCuv60724.

Frequently asked questions

What is CVE-2015-4321?: The Unicast Reverse Path Forwarding (uRPF) implementation in Cisco Adaptive Security Appliance (ASA) Software 9.3(1.50), 9.3(2.100), 9.3(3), and 9.4(1) mishandles cases where an IP address belongs to an internal interface but is also in the ASA routing table, which allows remote attackers to bypass uRPF validation via spoofed packets, aka Bug ID CSCuv60724.
How severe is CVE-2015-4321?: CVE-2015-4321 has a CVSS 2.0 base score of 5.0, rated medium severity.
Is CVE-2015-4321 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-4321?: CVE-2015-4321 primarily affects Cisco Adaptive Security Appliance Software. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2015-4321?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2015-4321 published?: CVE-2015-4321 was published on 2015-08-20 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:cisco:adaptive_security_appliance_software:9.3\(1.50\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.3\(2.100\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.3\(3\):*:*:*:*:*:*:*
cpe:2.3:o:cisco:adaptive_security_appliance_software:9.4\(1\):*:*:*:*:*:*:*

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