CVE-2025-6395Network attack vector

Remote server crash via omitted retry PSK

Published Jul 10, 2025 · Updated Sep 1, 2026

NULL pointer dereference in GnuTLS before 3.8.10 allows remote attackers to crash a TLS server through a crafted TLS 1.3 handshake. After a first Client Hello supplies a PSK and triggers a Hello Retry Request, a second Client Hello without that PSK leaves selected-PSK state referring to a cleared binder. The sequence requires no authentication, but constructing it is nontrivial; the demonstrated consequence is a server-process crash.

CVSS severity6.5
Medium
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in GnuTLS before 3.8.10 allows remote attackers to crash a TLS server through a crafted TLS 1.3 handshake. After a first Client Hello supplies a PSK and triggers a Hello Retry Request, a second Client Hello without that PSK leaves selected-PSK state referring to a cleared binder. The sequence requires no authentication, but constructing it is nontrivial; the demonstrated consequence is a server-process crash.

The record

CVE
CVE-2025-6395
Published
Jul 10, 2025
Updated
Sep 1, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 10, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 1, 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=V3.1.5 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*
389 Directory Server · Red Hat Ceph Storage 7Affected versions are unavailable in this record.
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
GnuTLS Project · GnuTLSversion=0 <3.8.10
389 Directory Server · Red Hat Enterprise Linux 9.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.4 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Insights proxy 1.5Affected versions are unavailable in this record.
389 Directory Server · Red Hat Discovery 2Affected versions are unavailable in this record.
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

6.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/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-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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