CVE-2023-0464Public exploitNetwork attack vector

Service interruption via unbounded policy-tree growth

Published Mar 22, 2023 · Updated May 5, 2025

Resource exhaustion in affected OpenSSL releases allows remote attackers to interrupt services with a malicious X.509 certificate chain. The X.509 policy engine builds a policy tree without bounding node creation, so crafted policy constraints cause exponential CPU and memory use. Policy processing must be enabled through the command-line policy option or X509_VERIFY_PARAM_set1_policies(); the bounded impact is interruption of the verifying service.

CVSS severity5.3
Medium
EPSS probability3.66%
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 affected OpenSSL releases allows remote attackers to interrupt services with a malicious X.509 certificate chain. The X.509 policy engine builds a policy tree without bounding node creation, so crafted policy constraints cause exponential CPU and memory use. Policy processing must be enabled through the command-line policy option or X509_VERIFY_PARAM_set1_policies(); the bounded impact is interruption of the verifying service.

The record

CVE
CVE-2023-0464
Published
Mar 22, 2023
Updated
May 5, 2025
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 22, 2023CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1.0.2 <1.0.2zh
  2. Affected versionversion=1.1.1 <1.1.1u
  3. Affected versionversion=3.0.0 <3.0.9
  4. Affected versionversion=3.1.0 <3.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenSSL Project · OpenSSLversion=1.0.2 <1.0.2zh; version=1.1.1 <1.1.1u; version=3.0.0 <3.0.9; version=3.1.0 <3.1.1

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitPublished

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

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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