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Routinator CVE-2021-43173

HIGH
Improper Handling of Exceptional Conditions (CWE-755)
2021-11-09 sep@nlnetlabs.nl
7.5
CVSS 3.1 · NVD
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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Exception handling procedures
Impact

CVSS score of 7.5 (HIGH). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.

Exploit ScenarioDerived

This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 1.4% exploitation probability (EPSS)

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AnalysisAI

In NLnet Labs Routinator prior to 0.10.2, a validation run can be delayed significantly by an RRDP repository by not answering but slowly drip-feeding bytes to keep the connection alive. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-755. In NLnet Labs Routinator prior to 0.10.2, a validation run can be delayed significantly by an RRDP repository by not answering but slowly drip-feeding bytes to keep the connection alive. This can be used to effectively stall validation. While Routinator has a configurable time-out value for RRDP connections, this time-out was only applied to individual read or write operations rather than the complete request. Thus, if an RRDP repository sends a little bit of data before that time-out expired, it can continuously extend the time it takes for the request to finish. Since validation will only continue once the update of an RRDP repository has concluded, this delay will cause validation to stall, leading to Routinator continuing to serve the old data set or, if in the initial validation run directly after starting, never serve any data at all. Affected products include: Nlnetlabs Routinator, Debian Debian Linux. Version information: prior to 0.10.2.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

DescriptionNVD

In NLnet Labs Routinator prior to 0.10.2, a validation run can be delayed significantly by an RRDP repository by not answering but slowly drip-feeding bytes to keep the connection alive. This can be used to effectively stall validation. While Routinator has a configurable time-out value for RRDP connections, this time-out was only applied to individual read or write operations rather than the complete request. Thus, if an RRDP repository sends a little bit of data before that time-out expired, it can continuously extend the time it takes for the request to finish. Since validation will only continue once the update of an RRDP repository has concluded, this delay will cause validation to stall, leading to Routinator continuing to serve the old data set or, if in the initial validation run directly after starting, never serve any data at all.

Threat Intelligence Overview

EPSS Score
1.4%
Top 30% exploitable
Data Quality
2 sources
Confidence: Low

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 1.4%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact· derived
Medium

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)NVD

cpe:2.3:a:nlnetlabs:routinator:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
CVE-2020-17366 HIGH POC
7.4 Aug 05

An issue was discovered in NLnet Labs Routinator 0.1.0 through 0.7.1. Rated high severity (CVSS 7.4), this vulnerability

CVE-2026-49235 HIGH
8.7 Jun 08

Denial of service in NLnet Labs Routinator allows remote attackers to crash the RPKI validator by serving a crafted Docu

CVE-2026-49232 HIGH
8.7 Jun 08

Denial of service in NLnet Labs Routinator allows remote unauthenticated attackers to crash the daemon by opening a larg

CVE-2026-49233 HIGH
8.3 Jun 08

Path traversal in NLnet Labs Routinator allows remote attackers to escape the rsync cache directory by supplying rsync U

CVE-2026-49234 HIGH
8.2 Jun 08

Denial of service in NLnet Labs Routinator (an RPKI Relying Party software) allows remote attackers to crash the daemon

CVE-2026-72753 HIGH
8.2 Oct 26

Routinator, NLnet Labs' RPKI relying party validator, mishandles RRDP notification files by accepting delta entries with

CVE-2026-72758 HIGH
7.5 Oct 26

Routinator, NLnet Labs' RPKI relying-party validator, can be driven into memory exhaustion by an AS range in RPKI data w

CVE-2026-72756 HIGH
7.5 Oct 26

Routinator exits when it encounters an RRDP-delivered rsync URI whose path cannot be stored on disk, producing a denial

CVE-2026-72754 HIGH
7.5 Oct 26

Routinator, NLnet Labs' RPKI relying-party validator, can be hung or terminated by a CRL fetched from the repository hie

CVE-2024-1622 HIGH
7.5 Feb 26

Due to a mistake in error checking, Routinator will terminate when an incoming RTR connection is reset by the peer too q

CVE-2023-39915 HIGH
7.5 Sep 13

NLnet Labs' Routinator up to and including version 0.12.1 may crash when trying to parse certain malformed RPKI objects.

CVE-2022-3029 HIGH
7.5 Sep 13

In NLnet Labs Routinator 0.9.0 up to and including 0.11.2, due to a mistake in error handling, data in RRDP snapshot and

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