How severe is CVE-2024-20436?

CVE-2024-20436 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-2024-20436 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-2024-20436?

CVE-2024-20436 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-2024-20436?

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.

Does CVE-2024-20436 have an EU (EUVD) identifier?

Yes. CVE-2024-20436 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-18151.

When was CVE-2024-20436 published?

CVE-2024-20436 was published on 2024-09-25 and last updated on 2026-06-17.

CVE-2024-20436

CVE-2024-20436 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-476.

Key facts

Severity: High (CVSS 3.x base score 8.6)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-18151
Weakness: CWE-476
Affected product: Cisco Ios Xe
Published: 2024-09-25
Last modified: 2026-06-17

Description

A vulnerability in the HTTP Server feature of Cisco IOS XE Software when the Telephony Service feature is enabled could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to a null pointer dereference when accessing specific URLs. An attacker could exploit this vulnerability by sending crafted HTTP traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, causing a DoS condition on the affected device.

Frequently asked questions

What is CVE-2024-20436?: A vulnerability in the HTTP Server feature of Cisco IOS XE Software when the Telephony Service feature is enabled could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to a null pointer dereference when accessing specific URLs. An attacker could exploit this vulnerability by sending crafted HTTP traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, causing a DoS condition on the affected device.
How severe is CVE-2024-20436?: CVE-2024-20436 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-2024-20436 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-2024-20436?: CVE-2024-20436 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-2024-20436?: 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.
Does CVE-2024-20436 have an EU (EUVD) identifier?: Yes. CVE-2024-20436 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-18151.
When was CVE-2024-20436 published?: CVE-2024-20436 was published on 2024-09-25 and last updated on 2026-06-17.

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-httpsrvr-dos-yOZThut

Affected products (201)

cpe:2.3:o:cisco:ios_xe:3.9.0as:*:*:*:*:*:*:*
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:3.10.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.10.2ts:*:*:*:*:*:*:*
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:3.13.2s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.3s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.4s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.5s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.6as:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.6s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.7s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.8s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.9s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.13.10s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.14.0s:*:*:*:*:*:*:*
cpe:2.3:o:cisco:ios_xe:3.14.1s:*:*:*:*:*:*:*

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