CVE-2023-39533Network attack vector

Unauthenticated service interruption via oversized RSA keys

Published Aug 8, 2023 · Updated Sep 1, 2026

Resource exhaustion in libp2p go-libp2p before 0.27.8, 0.28.0 through 0.28.1, and 0.29.0 allows remote attackers to interrupt nodes. The core/crypto UnmarshalRsaPublicKey path accepts a peer-supplied RSA modulus without a maximum size, causing handshake signature verification to consume excessive CPU. An unauthenticated peer must present the oversized key during a Noise handshake or libp2p x509 extension check; the bounded consequence is degraded or stalled node processing.

CVSS severity7.5
High
EPSS probability1.50%
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 libp2p go-libp2p before 0.27.8, 0.28.0 through 0.28.1, and 0.29.0 allows remote attackers to interrupt nodes. The core/crypto UnmarshalRsaPublicKey path accepts a peer-supplied RSA modulus without a maximum size, causing handshake signature verification to consume excessive CPU. An unauthenticated peer must present the oversized key during a Noise handshake or libp2p x509 extension check; the bounded consequence is degraded or stalled node processing.

The record

CVE
CVE-2023-39533
Published
Aug 8, 2023
Updated
Sep 1, 2026
Vendor
libp2p
Product
go-libp2p
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 8, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 1, 2026Record 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=< 0.27.8
  2. Affected versionversion=>= 0.28.0, < 0.28.2
  3. Affected versionversion== 0.29.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

libp2p · go-libp2pversion=< 0.27.8; version=>= 0.28.0, < 0.28.2; version== 0.29.0

Published CVSS scores

7.5GitHub, Inc.CVSS: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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