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Fencer Vulns
high 8.1

CVE-2020-3284 json

Cisco IOS XR Software Enhanced Preboot eXecution Environment Unsigned Code Execution Vulnerability

published 2020-11-06 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-24555

cvss
8.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.9%
EPSS 2.9% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

A vulnerability in the enhanced Preboot eXecution Environment (PXE) boot loader for Cisco IOS XR 64-bit Software could allow an unauthenticated, remote attacker to execute unsigned code during the PXE boot process on an affected device. The PXE boot loader is part of the BIOS and runs over the management interface of hardware platforms that are running Cisco IOS XR Software only. The vulnerability exists because internal commands that are issued when the PXE network boot process is loading a software image are not properly verified. An attacker could exploit this vulnerability by compromising the PXE boot server and replacing a valid software image with a malicious one. Alternatively, the attacker could impersonate the PXE boot server and send a PXE boot reply with a malicious file. A successful exploit could allow the attacker to execute unsigned code on the affected device. Note: To fix this vulnerability, both the Cisco IOS XR Software and the BIOS must be upgraded. The BIOS code is included in Cisco IOS XR Software but might require additional installation steps. For further information, see the Fixed Software section of this advisory.

Patch / fix

  • cisco a9k-rsp880-se_firmware 10.65
  • cisco ios_xr 1.12, 1.21, 6.5.2, 6.6.25, 7.0.2, 7.2.1
  • cisco a9k-rsp880-tr_firmware 10.65
  • cisco a99-rp2-se_firmware 14.35
  • cisco a99-rp2-tr_firmware 14.35
  • cisco a99-rsp-se_firmware 16.14
  • cisco a99-rsp-tr_firmware 16.14
  • cisco a9k-rsp880-lt-se_firmware 17.34
  • cisco a9k-rsp880-lt-tr_firmware 17.34
  • cisco asr-9901-rp_firmware 22.20
  • cisco a99-rp3-se_firmware 30.23
  • cisco a99-rp3-tr_firmware 30.23
  • cisco a9k-rsp5-se_firmware 31.20
  • cisco a9k-rsp5-tr_firmware 31.20
  • cisco ncs1001_firmware 14.60
  • cisco ncs1002_firmware 14.60
  • cisco ncs1004_firmware 14.60
  • cisco n540-12z20g-sys-a/d_firmware 1.15
  • cisco n540-24z8q2c-m_firmware 1.15
  • cisco n540-28z4c-sys-a/d_firmware 1.15

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 mo ago

Exploit prediction

2.89% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 9.3 AV:N/AC:M/Au:N/C:C/I:C/A:C

Affected products

  • Cisco Cisco IOS XR Software

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns 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.