How severe is CVE-2023-20187?

CVE-2023-20187 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-2023-20187 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-20187?

CVE-2023-20187 primarily affects Cisco Ios Xe. In total, 201 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-20187?

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-2023-20187 published?

CVE-2023-20187 was published on 2023-09-27 and last updated on 2026-06-17.

CVE-2023-20187

CVE-2023-20187 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-823.

Key facts

Severity: High (CVSS 3.x base score 8.6)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-823
Affected product: Cisco Ios Xe
Published: 2023-09-27
Last modified: 2026-06-17

Description

A vulnerability in the Multicast Leaf Recycle Elimination (mLRE) feature of Cisco IOS XE Software for Cisco ASR 1000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect handling of certain IPv6 multicast packets when they are fanned out more than seven times on an affected device. An attacker could exploit this vulnerability by sending a specific IPv6 multicast or IPv6 multicast VPN (MVPNv6) packet through the affected device. A successful exploit could allow the attacker to cause a reload of the affected device, resulting in a DoS condition.

Frequently asked questions

What is CVE-2023-20187?: A vulnerability in the Multicast Leaf Recycle Elimination (mLRE) feature of Cisco IOS XE Software for Cisco ASR 1000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause the affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to incorrect handling of certain IPv6 multicast packets when they are fanned out more than seven times on an affected device. An attacker could exploit this vulnerability by sending a specific IPv6 multicast or IPv6 multicast VPN (MVPNv6) packet through the affected device. A successful exploit could allow the attacker to cause a reload of the affected device, resulting in a DoS condition.
How severe is CVE-2023-20187?: CVE-2023-20187 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-2023-20187 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-20187?: CVE-2023-20187 primarily affects Cisco Ios Xe. In total, 201 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-20187?: 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-2023-20187 published?: CVE-2023-20187 was published on 2023-09-27 and last updated on 2026-06-17.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-mlre-H93FswRz

Affected products (201)

cpe:2.3:o:cisco:ios_xe:3.7.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.2ts:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.5s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.6s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.7.7s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.8.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.8.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.8.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.9.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.9.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.9.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.1xbs:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.5s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.6s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.7s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.8as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.8s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.9s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.10s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.11.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.11.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.11.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.11.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.11.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.12.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.12.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.12.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.12.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.12.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.1s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.2as:*:*:*:*:*:*:*

More vulnerabilities in Cisco Ios Xe

CVE-2025-20188 — Critical (CVSS 10.0): A vulnerability in the Out-of-Band Access Point (AP) Image Download, the Clean Air Spectral Recording, and the client…
CVE-2023-20198 — Critical (CVSS 10.0): Cisco is providing an update for the ongoing investigation into observed exploitation of the web UI feature in Cisco…
CVE-2021-34770 — Critical (CVSS 10.0): A vulnerability in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE…
CVE-2019-12643 — Critical (CVSS 10.0): A vulnerability in the Cisco REST API virtual service container for Cisco IOS XE Software could allow an…
CVE-2021-1619 — Critical (CVSS 9.8): A vulnerability in the authentication, authorization, and accounting (AAA) function of Cisco IOS XE Software could…
CVE-2020-3227 — Critical (CVSS 9.8): A vulnerability in the authorization controls for the Cisco IOx application hosting infrastructure in Cisco IOS XE…

All CVEs affecting Cisco Ios Xe →

Other CWE-823 vulnerabilities

CVE-2023-43553 — Critical (CVSS 9.8): Memory corruption while parsing beacon/probe response frame when AP sends more supported links in MLIE.
CVE-2026-46244 — Critical (CVSS 9.1): In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_inner: Fix IPv6 inner_thoff…
CVE-2025-27059 — High (CVSS 8.8): Memory corruption while performing SCM call.
CVE-2022-0729 — High (CVSS 8.8): Use of Out-of-range Pointer Offset in GitHub repository vim/vim prior to 8.2.4440.
CVE-2017-20211 — High (CVSS 8.6): UCanCode E-XD++ Visualization Enterprise Suite contains an untrusted pointer dereference vulnerability via the…
CVE-2025-0467 — High (CVSS 8.2): Kernel software installed and running inside a Guest VM may exploit memory shared with the GPU Firmware to write data…

Browse all CWE-823 vulnerabilities →