Security Resilience

CVE-2023-26463

Memory Safety in Strongswan 5.9.8 … 5.9.9

Published
15 April 2023
Modified
07 February 2025
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.023 83th percentile
Risk Priority 81 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-26463 is a critical-severity Improper Certificate Validation (CWE-295) vulnerability in Strongswan Strongswan. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique OS Credential Dumping (T1003); ranked in the top 17% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

strongSwan versions 5.9.8 and 5.9.9 contain a use-after-free vulnerability stemming from reuse of a variable named "public" for two distinct purposes inside the same function. The flaw manifests as an initial access-control bypass followed by an expired pointer dereference and is reachable only when the daemon loads plugins that implement TLS-based EAP methods (EAP-TLS, EAP-TTLS, EAP-PEAP, or EAP-TNC). The affected component is therefore any strongSwan server configured for these EAP methods.

An unauthenticated remote attacker can trigger the flaw by presenting a crafted client certificate during an EAP-TLS exchange. Successful exploitation yields remote code execution with the privileges of the charon process, enabling full compromise of the VPN gateway. The CVSS 3.1 base score of 9.8 reflects the absence of required authentication or user interaction and the complete confidentiality, integrity, and availability impact.

The issue is resolved in strongSwan 5.9.10; administrators are advised to upgrade immediately. Vendor advisories from strongSwan and NetApp reiterate that only servers exposing the listed EAP plugins are affected and that the fix eliminates the double use of the variable.

EPSS for the CVE rose from a low baseline to a peak of 0.1284 (currently 0.1154), indicating measurable post-disclosure exploitation interest that warrants renewed attention.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

strongSwan 5.9.8 and 5.9.9 potentially allows remote code execution because it uses a variable named "public" for two different purposes within the same function. There is initially incorrect access control, later followed by an expired pointer dereference. One attack vector…

more

is sending an untrusted client certificate during EAP-TLS. A server is affected only if it loads plugins that implement TLS-based EAP methods (EAP-TLS, EAP-TTLS, EAP-PEAP, or EAP-TNC). This is fixed in 5.9.10.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
T1003.007 Proc Filesystem Credential Access
Adversaries may gather credentials from the proc filesystem or `/proc`.
T1006 Direct Volume Access Stealth
Adversaries may directly access a volume to bypass file access controls and file system monitoring.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-78130Same product: Strongswan Strongswan
CVE-2026-78132Same product: Strongswan Strongswan
CVE-2023-41913Same product: Strongswan Strongswan
CVE-2026-78134Same product: Strongswan Strongswan
CVE-2026-78133Same product: Strongswan Strongswan
CVE-2026-39835Shared CWE-295, CWE-476
CVE-2026-25998Same vendor: Strongswan
CVE-2026-38974Shared CWE-295
CVE-2023-38353Shared CWE-295
CVE-2024-42193Shared CWE-295

Affected Assets

strongswan
strongswan
5.9.8, 5.9.9

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

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Detect
Catch it (NIST detect / respond)

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Harden
Shrink the surface (DISA STIG)
  • 12 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)

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Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-295

When certificates are used to establish component provenance, the control requires correct certificate validation procedures.

addresses: CWE-295

Mandates approved trust anchors and issuance policies, directly preventing acceptance of unvalidated or untrusted certificates.

addresses: CWE-295

Correct system time is required for proper enforcement of certificate notBefore/notAfter dates and time-based revocation checks.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-09 partial match
blocks

Assessing authenticity/integrity of acquired software often relies on code-signing certificate validation.

PR.AA-03 partial match
blocks

Certificate-based authentication of users/services/hardware directly depends on correct validation.

PR.AA-04 partial match
blocks

Identity assertions conveyed via certificates require validation to be verified.

PR.DS-02 partial match
blocks

Proper certificate validation is a core mechanism for protecting data-in-transit confidentiality and integrity.

PR.PS-06 partial match
blocks

Secure development practices explicitly include implementing correct certificate validation logic.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

removes
removes
removes
removes
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (3 rules)
  • V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. blocks CWE-295
  • V-248531 OL 8, for PKI-based authentication, must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor. blocks CWE-295
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-295
RHEL 7 (2 rules)
  • V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-295
  • V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-295
RHEL 8 (2 rules)
  • V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-295
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. blocks CWE-295

References