What is CVE-2026-33826?
A stack-based buffer overflow in the Windows IKE Extensions service (IKEEXT) allows an unauthenticated remote attacker to achieve code execution by sending a malformed IKE_SA_INIT packet. The vulnerability is in the IKEv2 negotiation parser and requires no user interaction or authentication. The network-adjacent attack vector and lack of required privileges make this a critical-severity issue with potential for wormable exploitation across enterprise VPN and IPsec infrastructure.
The record classifies CVE-2026-33826 under weakness class CWE-121. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 197 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9.1 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N - EPSS (FIRST)
- 0.5% probability of exploitation in the next 30 days, higher than 43.7% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 8.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-04-14, last modified 2026-09-25
Is CVE-2026-33826 being exploited?
Weaponised exploit code for CVE-2026-33826 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 24 in the Threadlinqs vulnerability feed.
- kaleth4/CVE-2026-33826 (github)
Affected products and versions
- Microsoft: Windows IKE Extensions (IKEEXT)
How to fix CVE-2026-33826
The record marks a vendor fix as available for CVE-2026-33826. Patch reference: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33826. Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-33826. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-33826
2 tracked threats in the Threadlinqs corpus reference CVE-2026-33826, either in the campaign’s CVE list or as an indicator on the campaign record.
- Microsoft April 2026 Patch Tuesday — 163 CVEs / 88 Advisories (CVE-2026-32201 SharePoint Zero-Day Exploited In-The-Wild, CVE-2026-33825 Defender EoP Public PoC, CVE-2026-33824 IKE RCE CVSS 9.8, CVE-2026-33827 TCP/IP Wormable RCE) — CRITICAL · 2026-04-19
- Microsoft April 2026 Patch Tuesday — 167 Flaws, 2 Zero-Days (SharePoint Spoofing CVE-2026-32201 + Defender EoP CVE-2026-33825) — CRITICAL · 2026-04-14
Sources
Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on .