CVE-2024-5535Network attack vector

Memory disclosure via empty protocol list overread

Published Jun 27, 2024 · Updated May 12, 2026

Buffer overread in OpenSSL allows attackers to receive up to 255 bytes of process memory when a calling application exposes the result. SSL_select_next_proto accepts client_len 0 and returns memory immediately after the client-list pointer as the first no-overlap protocol. Exposure requires an erroneous ALPN callback or an NPN client with an empty application-supplied list; normal ALPN input is unaffected.

CVSS severity5.9
Medium
EPSS probability5.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overread in OpenSSL allows attackers to receive up to 255 bytes of process memory when a calling application exposes the result. SSL_select_next_proto accepts client_len 0 and returns memory immediately after the client-list pointer as the first no-overlap protocol. Exposure requires an erroneous ALPN callback or an NPN client with an empty application-supplied list; normal ALPN input is unaffected.

The record

CVE
CVE-2024-5535
Published
Jun 27, 2024
Updated
May 12, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-200
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 27, 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=V3.1.0 <V3.1.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIMATIC S7-1500 TM MFP - GNU/Linux subsystemversion=0 <*
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SCALANCE XCM/XRM/XCH/XRH-300 familyversion=0 <V3.1
OpenSSL Project · OpenSSLversion=1.0.2 <1.0.2zk; version=1.1.1 <1.1.1za; version=3.0.0 <3.0.15; version=3.1.0 <3.1.7; version=3.2.0 <3.2.3; version=3.3.0 <3.3.2
Siemens · RUGGEDCOM RST2428Pversion=0 <V3.1
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.0 <V3.1.5
Siemens · SIDIS Primeversion=0 <V4.0.700

Published CVSS scores

5.9Siemens ProductCERTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/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 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-200Exposure of Sensitive Information to an Unauthorized Actor

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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