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Fencer Intel
medium 6.0

CVE-2021-34709 json

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

published 5y ago modified 4mo ago also EUVD-2021-21359

cvss
6.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

Multiple vulnerabilities in image verification checks of Cisco Network Convergence System (NCS) 540 Series Routers, only when running Cisco IOS XR NCS540L software images, and Cisco IOS XR Software for Cisco 8000 Series Routers could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system. For more information about these vulnerabilities, see the Details section of this advisory.

Patch / fix

  • cisco ios_xr 7.3.2, 7.4.1

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2y ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.0 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
NVD 3.1 6.4 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Affected products

  • Cisco Cisco IOS XR Software

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.