Cisco IOS XE Software Blocks Extensible Exchange Protocol Denial of Service Vulnerability

highCVE-2026-20263

A vulnerability in the Blocks Extensible Exchange Protocol (BEEP) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling when parsing a specific BEEP SOAP request. An attacker could exploit this vulnerability by sending a specific BEEP SOAP request to an affected device. A successful exploit could allow the attacker to cause the device to reload unexpectedly, resulting in a DoS condition. Cisco has released software updates that address this vulnerability. There are no workarounds that address these vulnerabilities. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-bing-MGHrFAkd Security Impact Rating: High CVE: CVE-2026-20263

CSIRTS triage

vendor: Cisco product: IOS XE Software Denial of service

What: Improper handling of malformed BEEP SOAP requests in the Blocks Extensible Exchange Protocol feature causes device reload.
Who is affected: Unauthenticated remote attackers can target any IOS XE device with BEEP enabled.
Urgency: High severity; unauthenticated remote denial of service causing device reload.
Action: Apply Cisco IOS XE Software updates; no workarounds available.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Cisco Security Advisories (INTL · vendor-psirt · site)
Severity: high
Published: 2026-08-05
Exploitation: Not in CISA KEV at last sync

Original advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-bing-MGHrFAkd?vs_f=Cisco%20Security%20Advisory%26vs_cat=Security%20Intelligence%26vs_type=RSS%26vs_p=Cisco%20IOS%20XE%20Software%20Blocks%20Extensible%20Exchange%20Protocol%20Denial%20of%20Service%20Vulnerability%26vs_k=1

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-202630.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-20263	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[NEW] [high] Cisco IOS XE: Multiple Vulnerabilitiescert-bund
unknownCisco Products Multiple Vulnerabilitieshkcert
unknownMultiple vulnerabilities in Cisco products (August 6, 2026)cert-fr-avis
highCVE-2026-20263: A vulnerability in the Blocks Extensible Exchange Protocol (BEEP) feature of Cisco IOS XE Soft…nvd
criticalCisco Advance Notification for Publication of August 5, 2026, Security Advisoriescisco-psirt

Recent advisories for Cisco IOS XE

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

unknownMultiple vulnerabilities in Cisco IOS XE (August 25, 2026)cert-fr-avis · 2026-08-25
unknownNCSC-2026-0279 [1.00] [M/H] Vulnerabilities patched in Cisco IOS XE Softwarencsc-nl · 2026-08-07
high[NEW] [high] Cisco IOS XE: Multiple Vulnerabilitiescert-bund · 2026-08-06
mediumCVE-2026-20311: A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an …nvd · 2026-08-05
mediumCVE-2026-20308: A vulnerability in the web-based management interface of Cisco IOS XE Software could allow an …nvd · 2026-08-05
highCVE-2026-20301: A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the Ex…nvd · 2026-08-05