CVE-2021-1313Network attack vector

Service interruption via packet-triggered memory exhaustion

Published Feb 4, 2021 · Updated Nov 8, 2024

Resource exhaustion in Cisco IOS XR Software allows remote attackers to crash enf_broker through crafted ICMP or Telnet streams. Ingress packet processing allocates resources improperly for either protocol, leaking system memory until the process fails. IPv4 or IPv6 reachability is sufficient; the crash destabilizes the device and prevents traffic processing or forwarding.

CVSS severity8.6
High
EPSS probability1.95%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Cisco IOS XR Software allows remote attackers to crash enf_broker through crafted ICMP or Telnet streams. Ingress packet processing allocates resources improperly for either protocol, leaking system memory until the process fails. IPv4 or IPv6 reachability is sufficient; the crash destabilizes the device and prevents traffic processing or forwarding.

The record

CVE
CVE-2021-1313
Published
Feb 4, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-401, CWE-399, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=n/a

Published CVSS scores

8.6Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
CWE-399Resource Management Errors
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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