CVE-2021-45699Network attack vector

Remote node crash via unbounded peer-state growth

Published Dec 26, 2021 · Updated Aug 4, 2024

Memory exhaustion in Nervos CKB before 0.40.0 allows remote attackers to crash a node through repeated peer connections. The sync protocol's SyncState stores violation scores in the misbehavior HashMap under monotonically increasing SessionId keys and never removes entries. Unauthenticated network access is sufficient to grow the map until allocation panics or the operating system kills the process, interrupting the node and potentially reducing network hash power.

CVSS severity7.5
High
EPSS probability1.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exhaustion in Nervos CKB before 0.40.0 allows remote attackers to crash a node through repeated peer connections. The sync protocol's SyncState stores violation scores in the misbehavior HashMap under monotonically increasing SessionId keys and never removes entries. Unauthenticated network access is sufficient to grow the map until allocation panics or the operating system kills the process, interrupting the node and potentially reducing network hash power.

The record

CVE
CVE-2021-45699
Published
Dec 26, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NIST NVDCVSS: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 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-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

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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