“We’ll catch the next change window” turns into an incident when a CVSS 10 in the SAP kernel ships with a public exploitation toolkit — weeks after Patch Day.
“We’ll catch the next change window” turns into an incident.
OVERPASS (CVE-2026-44756) is unauthenticated remote code execution via malformed Extended Passport (EPP) data in shared kernel code. Onapsis also flagged S4GET (CVE-2026-58240, CVSS 9.8) on the NetWeaver Message Server. SAPMAP now ships PoCs for both.
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What happened
SAP’s September 8, 2026 Patch Day included HotNews Note 3747649 for OVERPASS: missing boundary validation when deserializing EPP lets an unauthenticated attacker send a crafted request and achieve high-impact compromise (Onapsis: OS command execution as the SAP admin OS account). EPP is processed at session open — before auth — and is reachable over HTTP (ICM/Web Dispatcher), SAP GUI/DIAG, and RFC. One kernel patch closes all routes.
S4GET (Note 3759472, CVE-2026-58240) is missing authentication when the Message Server registers application-server components — unauth network attackers can register unauthorized components. It hits modern kernel family 9.16–9.20 (S/4HANA 2025 and earlier moves to those kernels).
Onapsis updated guidance through September 21: the SAPMAP toolkit includes PoC exploits for OVERPASS and S4GET. Onapsis had not observed in-the-wild exploitation as of that update — PoC publication is the clock speeding up.
Why it matters
Shared kernel code means ERP, S/4HANA, Solution Manager, PI/PO, portals, and Web Dispatcher inherit the flaw. Onapsis estimates 10,000+ Internet-facing SAP web interfaces as a conservative count — and the SAP GUI route exposes essentially every ABAP system internally even when nothing is published. Authorizations and SoD do not help: the bug runs before they evaluate. History (ICMAD, RECON, CVE-2025-31324) says SAP criticals get reverse-engineered fast once patches and toolkits are out.
What to do first
- Inventory every SAP system’s kernel release/patch level against Note 3747649 (and 3759472 for Message Server) — include non-prod and “forgotten” boxes.
- Patch Internet-facing ICM/Web Dispatcher / Fiori / WebGUI systems first; then internal app servers (GUI route is universal).
- RISE customers: file the downtime CSR promptly so the provider can schedule the kernel reboot.
- Apply FAQ Note 3776034 and HTTP-oriented workarounds in 3756304 only as temporary risk reduction — not a substitute for the kernel patch.
- Enable SAP application-layer monitoring for exploit attempts during rollout; preserve forensic evidence before wipe-and-patch if compromise is suspected.
Forward this — BASIS / SAP owners: patch Internet-facing ICM/Web Dispatcher systems against Note 3747649 first; PoCs are already in SAPMAP.
Details
- CVE-2026-44756 (OVERPASS): Memory corruption in EPP processing — CVSS 10.0 — Note 3747649
- CVE-2026-58240 (S4GET): Missing auth on Message Server registration — CVSS 9.8 — Note 3759472
- Vectors (OVERPASS): HTTP/ICM, SAP GUI/Dispatcher, RFC — all pre-auth
- PoC status: SAPMAP toolkit includes exploits (Onapsis, updated 2026-09-21)
- In-the-wild: Not observed by Onapsis as of latest advisory update
Hunt / verify
- Confirm kernel patch level matches Note 3747649 / 3759472 fixed builds post-change.
- Review Internet-facing SAP fingerprints and Message Server exposure; restrict Dispatcher behind SAProuter/jump hosts where possible.
- Watch for anomalous pre-auth traffic carrying abnormal EPP-related payloads and unexpected app-server registrations on the Message Server.
Slack paste: Confirm Note 3747649 / 3759472 kernel levels; patch Internet-facing ICM/Web Dispatcher first; watch pre-auth EPP + Message Server registrations.
Sources
- https://onapsis.com/blog/sap-overpass-remediation/
- https://onapsis.com/blog/sap-security-patch-day-september-2026/
- https://onapsis.com/blog/s4get-cve-2026-58240-sap-message-server-threat-advisory/
- https://support.sap.com/en/my-support/knowledge-base/security-notes-news/september-2026.html
- https://cert.europa.eu/publications/security-advisories/2026-011/
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