Read the docs
TI-2021-00863 Aliases CVE-2021-1136GHSA-hrm7-r95m-mcv4

Improper signature verification in Cisco IOS XR Software

Priority LOW 31CWE-347Published · Updated

Key facts

Attack vector
Local
Privileges required
High
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-347.

Summary

Multiple vulnerabilities in Cisco Network Convergence System (NCS) 540 Series Routers, only when running Cisco IOS XR NCS540L software images, and Cisco IOS XR Software for the Cisco 8000 Series Routers could allow an authenticated, local attacker to execute unsigned code during the boot process on an affected device. For more information about these vulnerabilities, see the Details section of this advisory.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00207 10th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
CiscoCisco IOS XR Softwareall versions—No fix listedCNA
  • Cisco IOS XR Software VendorCisco Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 8

CPEVersionsRoleVendor
cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*before 7.0.12; 7.1.0 to before 7.2.1VulnerableCisco
cpe:2.3:h:cisco:8201:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:8202:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:8808:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:8812:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:h:cisco:8818:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*before 7.2.1VulnerableCisco
cpe:2.3:h:cisco:ncs_540:-:*:*:*:*:*:*:*not specified by NVDRunning onCisco
  • cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* Versions before 7.0.12; 7.1.0 to before 7.2.1 Vulnerable ·Cisco
  • cpe:2.3:h:cisco:8201:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:8202:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:8808:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:8812:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:h:cisco:8818:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
  • cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* Versions before 7.2.1 Vulnerable ·Cisco
  • cpe:2.3:h:cisco:ncs_540:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco

Remediation

No fixed version listed by the sources yet.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Cisco IOS XR Software — 20210203 Cisco IOS XR Software for Cisco 8000 Series Routers and Network Convergence System 540 Series Routers Image Verification Vulnerabilities

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2021-00971 Improper signature verification in Cisco IOS XR SoftwarePriority LOW 31
    Show all 2 records → Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-1136
  2. 2026-10-03 Alias added: GHSA-hrm7-r95m-mcv4

References

Advisory 1

  • TI-2020-02680 Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
  • TI-2020-03113 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerabilities KEVCVSS 3.1HIGH 8.6
  • TI-2020-03110 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability KEVCVSS 3.1HIGH 8.6
  • TI-2018-00142 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.0
  • TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
See all 199 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences