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Full vulnerability report · 2023
CVE-2023-25136High confidence

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling

n/a · n/a

6.5MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
SSA-398330 · CSAF 2.0 · revision 18 · interimSiemens ProductCERTSSA-398330: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP >= V3.1.0 and < V3.1.5
5 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)
  • SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)
  • SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)
  • SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)
Summary
OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."
Remediation
Update to V3.1.5 or later version
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2023-29115

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

What

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

Why

The product calls free() twice on the same memory address.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be leveraged, by an unauthenticated remote attacker in the default configuration, to jump to any location in the sshd address space. One third-party report states "remote code execution is theoretically possible."

Why

The product calls free() twice on the same memory address.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Double Free → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-415 ↗

CWE-415: Double Free. The product calls free() twice on the same memory address.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-415Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2023-1542Red Hat OpenShift: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Red Hat OpenShift ausnutzen, um einen Denial of Service Zustand herbeizuführen, Informationen offenzulegen, Dateien zu manipulieren oder Sicherheitsvorkehrungen zu umgehen.

Official advisory
BSI · German · WID-SEC-W-2023-0279OpenSSH: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in OpenSSH ausnutzen, um beliebigen Programmcode auszuführen und um Sicherheitsmechanismen zu umgehen.

Official advisory
CERT-FR · French · CERTFR-2023-AVI-1015Multiples vulnérabilités dans les produits Siemens

/CVERecord?id=CVE-2023-0465 Référence CVE CVE-2023-0466 https://www.cve.org/CVERecord?id=CVE-2023-0466 Référence CVE CVE-2023-0687 https://www.cve.org/CVERecord?id=CVE-2023-0687 Référence CVE CVE-2023-1077 https://www.cve.org/CVERecord?id=CVE-2023-1077 Référence CVE CVE-2023-1206 https://www.cve.org/CVERecord?id=CVE-2023-1206 Référence CVE CVE-2023-23914 https://www.cve.org/CVERecord?id=CVE-2023-23914 Référence CVE CVE-2023-23915 https://www.cve.org/CVERecord?id=CVE-2023-23915 Référence CVE CVE-2023-23916 https://www.cve.org/CVERecord?id=CVE-2023-23916 Référence CVE CVE-2023-24329 https://www.cve.org/CVERecord?id=CVE-2023-24329 Référence CVE CVE-2023-25136 https://www.cve.org/CVERecord?id=CVE-2023-25136 Référence CVE CVE-2023-25139 https://www.cve.org/CVERecord?id=CVE-2023-25139 Référence CVE CVE-2023-2650 https://www.cve.org/CVERecord?id=CVE-2023-2650 Référence CVE CVE-2023-26604 https://www.cve.org/CVERecord?id=CVE-2023-26604 Référence CVE CVE-2023-27371 https://www.cve.org/CVERecord?id=CVE-2023-27371 Référence CVE CVE-2023-27533 https://www.cve.org/CVERecord?id=CVE-2023-27533 Référence CVE CVE-2023-27534 https://www.cve.org/CVERecord?id=CVE-2023-27534 Référence CVE CVE-2023-27535 https://www.cve.org/CVERecord?id=CVE-2023-27535 Référence CVE CVE-2023-27536 https://www.cve.org/CVERecord?id=CV

Official advisory
CERT-FR · French · CERTFR-2023-AVI-0272Multiples vulnérabilités dans les produits IBM

d?id=CVE-2022-41717 Référence CVE CVE-2022-41720 https://www.cve.org/CVERecord?id=CVE-2022-41720 Référence CVE CVE-2022-41721 https://www.cve.org/CVERecord?id=CVE-2022-41721 Référence CVE CVE-2022-41722 https://www.cve.org/CVERecord?id=CVE-2022-41722 Référence CVE CVE-2022-41723 https://www.cve.org/CVERecord?id=CVE-2022-41723 Référence CVE CVE-2022-41724 https://www.cve.org/CVERecord?id=CVE-2022-41724 Référence CVE CVE-2022-41725 https://www.cve.org/CVERecord?id=CVE-2022-41725 Référence CVE CVE-2022-41727 https://www.cve.org/CVERecord?id=CVE-2022-41727 Référence CVE CVE-2022-42898 https://www.cve.org/CVERecord?id=CVE-2022-42898 Référence CVE CVE-2023-25136 https://www.cve.org/CVERecord?id=CVE-2023-25136 Référence CVE CVE-2023-27589 https://www.cve.org/CVERecord?id=CVE-2023-27589 Gestion détaillée du document le 30 mars 2023 Version initiale Alertes Avis Bulletins d’actualités Mentions légales Conditions générales À propos Contact cyber.gouv.fr service-public.fr legifrance.gouv.fr info.gouv.fr france.fr info.gouv.fr/risques Premier Ministre / Secrétariat Général de la Défense et de la Sécurité Nationale / Agence nationale de la sécurité des systèmes d'information

Official advisory
CERT-FR · French · CERTFR-2023-AVI-0089Multiples vulnérabilités dans OpenSSH

De multiples vulnérabilités ont été découvertes dans OpenSSH. Elles permettent à un attaquant de provoquer un problème de sécurité non spécifié par l'éditeur et un contournement de la politique de sécurité.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0); SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0); SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0); SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0); SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)
Fixed
An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
Action
Update to V3.1.5 or later version
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 3 Feb 2023 · Last source change 28 May 2026, 17:43 UTC · CWE-415 · Double Free

CVE recordCVE.org · 5.2
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2023-29115
Product sourceVendor CSAF · Siemens ProductCERT
Remediation sourceVendor CSAF · Siemens ProductCERT
CWE sourceCISA ADP
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2023-29115↗Vendor CSAF · Siemens ProductCERT↗CISA Vulnrichment SSVC evidence↗CVE authority or vendor reference↗Patch or update reference↗Public exploit reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2023-25136 · cve.blacktree.nl