CVE-2026-25075Network attack vector

Unauthenticated daemon crash via malformed AVP length

Published Mar 23, 2026 · Updated Mar 23, 2026

Integer underflow in strongSwan 4.5.0 through 6.0.4 allows remote attackers to crash the charon daemon via crafted EAP-TTLS AVPs. The EAP-TTLS AVP process method subtracts the eight-byte header size without first rejecting lengths below eight, producing a huge allocation length and a NULL dereference. The eap-ttls plugin must be enabled and reachable during IKEv2 authentication; no credentials or user interaction are required, and the consequence is a VPN service interruption.

CVSS severity8.7
High
EPSS probability1.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in strongSwan 4.5.0 through 6.0.4 allows remote attackers to crash the charon daemon via crafted EAP-TTLS AVPs. The EAP-TTLS AVP process method subtracts the eight-byte header size without first rejecting lengths below eight, producing a huge allocation length and a NULL dereference. The eap-ttls plugin must be enabled and reachable during IKEv2 authentication; no credentials or user interaction are required, and the consequence is a VPN service interruption.

The record

CVE
CVE-2026-25075
Published
Mar 23, 2026
Updated
Mar 23, 2026
Vendor
strongSwan
Product
strongSwan
Classifications
CWE-191, CWE-476, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 23, 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=4.5.0 <6.0.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

strongSwan · strongSwanversion=4.5.0 <6.0.5

Published CVSS scores

7.5VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

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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