CVE-2021-43173Network attack vector

RPKI validation stall via slow-drip RRDP response

Published Nov 9, 2021 · Updated Sep 16, 2024

Denial of service in NLnet Labs Routinator 0.10.1 and earlier allows remote attackers to stall RPKI validation via an RRDP repository. The RRDP client applies its configured timeout to each read or write instead of the complete request, letting periodic bytes extend one update indefinitely. Exploitation requires control of a repository used during validation and leaves existing instances serving stale data, while an initial run serves no data.

CVSS severity7.5
High
EPSS probability1.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in NLnet Labs Routinator 0.10.1 and earlier allows remote attackers to stall RPKI validation via an RRDP repository. The RRDP client applies its configured timeout to each read or write instead of the complete request, letting periodic bytes extend one update indefinitely. Exploitation requires control of a repository used during validation and leaves existing instances serving stale data, while an initial run serves no data.

The record

CVE
CVE-2021-43173
Published
Nov 9, 2021
Updated
Sep 16, 2024
Vendor
NLnet Labs
Product
Routinator
Classifications
CWE-755, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=unspecified <=0.10.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NLnet Labs · Routinatorversion=unspecified <=0.10.1

Published CVSS scores

7.5UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499Endpoint Denial of Service

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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