CVE-2023-6237Network attack vector

Denial of service via oversized prime RSA modulus

Published Apr 25, 2024 · Updated May 12, 2026

Resource exhaustion in OpenSSL 3.0.0 through 3.0.12, 3.1.0 through 3.1.4, and 3.2.0 allows attackers to cause long delays. EVP_PKEY_public_check() attempts to prove that an untrusted RSA modulus is composite without first limiting its size, so an overly large prime forces a prolonged computation. Exposure requires an application to pass attacker-controlled keys to that API, or use the pkey command with -pubin and -check; TLS processing is unaffected and the bounded consequence is a service hang.

CVSS severity5.9
Medium
EPSS probability2.30%
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 OpenSSL 3.0.0 through 3.0.12, 3.1.0 through 3.1.4, and 3.2.0 allows attackers to cause long delays. EVP_PKEY_public_check() attempts to prove that an untrusted RSA modulus is composite without first limiting its size, so an overly large prime forces a prolonged computation. Exposure requires an application to pass attacker-controlled keys to that API, or use the pkey command with -pubin and -check; TLS processing is unaffected and the bounded consequence is a service hang.

The record

CVE
CVE-2023-6237
Published
Apr 25, 2024
Updated
May 12, 2026
Vendor
Siemens
Product
SINEC NMS
Classifications
CWE-606, CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 25, 2024CVE publishedPublication date reported by the CVE source.
  2. May 12, 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 <V3.0 SP1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SINEC NMSversion=0 <V3.0 SP1
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
OpenSSL Project · OpenSSLversion=3.0.0 <3.0.13; version=3.1.0 <3.1.5; version=3.2.0 <3.2.1

Published CVSS scores

5.9CISA-ADPCVSS:3.1/AV:N/AC:H/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-606Unchecked Input for Loop Condition
CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

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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