How severe is CVE-2020-3203?

CVE-2020-3203 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-3203 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3203?

CVE-2020-3203 primarily affects Cisco Ios Xe. In total, 54 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3203?

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-2020-3203 published?

CVE-2020-3203 was published on 2020-06-03 and last updated on 2026-06-17.

CVE-2020-3203

CVE-2020-3203 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 8.6. 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-401.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.8
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Cisco Ios Xe
Published: 2020-06-03
Last modified: 2026-06-17

Description

A vulnerability in the locally significant certificate (LSC) provisioning feature of Cisco Catalyst 9800 Series Wireless Controllers that are running Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a memory leak that could lead to a denial of service (DoS) condition. The vulnerability is due to incorrect processing of certain public key infrastructure (PKI) packets. An attacker could exploit this vulnerability by sending crafted Secure Sockets Layer (SSL) packets to an affected device. A successful exploit could cause an affected device to continuously consume memory, which could result in a memory allocation failure that leads to a crash and causes a DoS condition.

Frequently asked questions

What is CVE-2020-3203?: A vulnerability in the locally significant certificate (LSC) provisioning feature of Cisco Catalyst 9800 Series Wireless Controllers that are running Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a memory leak that could lead to a denial of service (DoS) condition. The vulnerability is due to incorrect processing of certain public key infrastructure (PKI) packets. An attacker could exploit this vulnerability by sending crafted Secure Sockets Layer (SSL) packets to an affected device. A successful exploit could cause an affected device to continuously consume memory, which could result in a memory allocation failure that leads to a crash and causes a DoS condition.
How severe is CVE-2020-3203?: CVE-2020-3203 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-3203 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3203?: CVE-2020-3203 primarily affects Cisco Ios Xe. In total, 54 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3203?: 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-2020-3203 published?: CVE-2020-3203 was published on 2020-06-03 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-ewlc-dos-TkuPVmZN

Affected products (54)

cpe:2.3:o:cisco:ios_xe:16.1.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.1.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.1.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.2.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.2.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.4:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.5:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.5b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.6:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.7:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.8:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.3.9:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.4.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.4.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.4.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.5.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.5.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.5.1b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.5.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.5.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.7.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.1b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.1c:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.8.3:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.1a:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.1b:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.1e:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:16.10.2:*:*:*:*:*:*:*

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