Strongswan is a widely deployed open-source IPsec implementation used for VPN and secure communication across enterprise networks and embedded systems, despite maintaining a narrow product line. Vulnerabilities affecting the vendor skew strongly toward critical-severity outcomes and concentrate in the core Strongswan daemon and VPN client, where they recur through weakness classes including improper input validation, buffer boundary violations, improper authentication, and cryptographic signature verification failures—flaws that reflect the parsing and cryptographic complexity inherent to IPsec protocol handling. The vendor's exposure is significant relative to its modest CVE volume because IPsec sits on network perimeters and in remote-access paths where a single implementation flaw can compromise the confidentiality and authenticity guarantees the protocol is meant to provide. Defenders should prioritize Strongswan patching in gateway and client deployments and treat protocol-level vulnerabilities as high-risk; live severity, exploitation, and exposure counts are shown alongside this summary.
The number and severity of CVEs published that impact products developed by Strongswan over time
Signals from CVEs in this vendor scope (40 CVEs).
40 CVEs · Highest risk first
| CVE | Published | CVSS | Risk | KEV | Exploit |
|---|---|---|---|---|---|
CVE-2026-25075HIGH strongSwan versions 4.5.0 prior to 6.0.5 contain an integer underflow vulnerability in the EAP-TTLS AVP parser that allows unauthenticated remote attackers to cause a denial of ser | Mar 23, 2026 | 7.5 | 32 | NO | NO |
CVE-2023-26463CRITICAL 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 initiall | Apr 15, 2023 | 9.8 | 32 | NO | NO |
CVE-2023-41913CRITICAL strongSwan before 5.9.12 has a buffer overflow and possible unauthenticated remote code execution via a DH public value that exceeds the internal buffer in charon-tkm's DH proxy. T | Dec 7, 2023 | 9.8 | 31 | NO | NO |
CVE-2021-45079CRITICAL In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too early without actually authenticating the client and (in the case of EAP methods with mutual a | Jan 31, 2022 | 9.1 | 30 | NO | NO |
CVE-2025-62291HIGH In the eap-mschapv2 plugin (client-side) in strongSwan before 6.0.3, a malicious EAP-MSCHAPv2 server can send a crafted message of size 6 through 8, and cause an integer underflow | Jan 16, 2026 | 8.1 | 28 | NO | NO |
CVE-2021-41991HIGH The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigge | Oct 18, 2021 | 7.5 | 27 | NO | NO |
CVE-2021-41990HIGH The gmp plugin in strongSwan before 5.9.4 has a remote integer overflow via a crafted certificate with an RSASSA-PSS signature. For example, this can be triggered by an unrelated s | Oct 18, 2021 | 7.5 | 27 | NO | NO |
CVE-2018-10811HIGH strongSwan 5.6.0 and older allows Remote Denial of Service because of Missing Initialization of a Variable. | Jun 19, 2018 | 7.5 | 27 | NO | NO |
CVE-2022-40617HIGH strongSwan before 5.9.8 allows remote attackers to cause a denial of service in the revocation plugin by sending a crafted end-entity (and intermediate CA) certificate that contain | Oct 31, 2022 | 7.5 | 26 | NO | NO |
CVE-2026-25998HIGH strongMan is a management interface for strongSwan, an OpenSource IPsec-based VPN. When storing credentials in the database (private keys, EAP secrets), strongMan encrypts the corr | Feb 19, 2026 | 7.5 | 25 | NO | NO |
Signals from CVEs in this vendor scope (40 CVEs).
An overview of all social media posts that mention a CVE ID that affects a product developed by Strongswan.
Media articles that mention a CVE ID that affects a product developed by Strongswan — matched by CVE ID, not by vendor name.