CVE-2023-0465Network attack vector

Certificate-policy bypass via skipped leaf validation

Published Mar 28, 2023 · Updated Feb 18, 2025

Improper certificate validation in affected OpenSSL releases allows remote attackers to bypass certificate-policy checks using a malicious CA. In crypto/x509/x509_vfy.c, check_policy starts its invalid-policy scan at chain index 1, omitting the leaf at index 0 and returning success despite EXFLAG_INVALID_POLICY. Exploitation requires non-default policy processing and trust in the malicious CA; a crafted leaf certificate can then pass checks that should reject it.

CVSS severity5.3
Medium
EPSS probability1.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in affected OpenSSL releases allows remote attackers to bypass certificate-policy checks using a malicious CA. In crypto/x509/x509_vfy.c, check_policy starts its invalid-policy scan at chain index 1, omitting the leaf at index 0 and returning success despite EXFLAG_INVALID_POLICY. Exploitation requires non-default policy processing and trust in the malicious CA; a crafted leaf certificate can then pass checks that should reject it.

The record

CVE
CVE-2023-0465
Published
Mar 28, 2023
Updated
Feb 18, 2025
Vendor
OpenSSL Project
Product
OpenSSL
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 18, 2025Record 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=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

5.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.3CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.3Oracle LinuxCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

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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