PT-2026-24730 · Cisco · Ios Xr

Published 2026-03-11 · Updated 2026-03-13 · CVE-2026-20074

Positive Technologies (AI Summary)

CVSS v3.1

7.4

High

Base vector

AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Cisco IOS XR Software (affected versions not specified)

Description A flaw exists in the Intermediate System-to-Intermediate System (IS-IS) multi-instance routing feature that could allow a nearby, unauthenticated attacker to unexpectedly restart the IS-IS process. This is due to inadequate validation of incoming IS-IS packets. An attacker can exploit this by sending specially crafted IS-IS packets to a vulnerable device after establishing a connection. A successful exploit could lead to a temporary loss of network connectivity and a denial-of-service (DoS) condition. The IS-IS protocol is a routing protocol, and an attacker must be on Layer 2 of the network and have established a connection with the affected device to exploit this issue.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

DoS

Weakness Enumeration

CWE-1287

Related Identifiers

BDU:2026-05200

CVE-2026-20074

Affected Products

Ios Xr

References · 6

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-isis-dos-kDMxpSzK · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-20074 · Security Note
• https://bdu.fstec.ru/vul/2026-05200 · Security Note
• https://t.me/CVEtracker/47137 · Telegram Post
• https://reddit.com/r/pwnhub/comments/1rrw3gg/cisco_patches_four_highseverity_ios_xr · Reddit Post
• https://twitter.com/CVEnew/status/2032410993343762608 · Twitter Post