Improper verification of JWT signature in IASContextProvider leads to tenant/user identity spoofing ( sap-cloud-sdk (pip))
Affects sap-cloud-sdk for Python (pip) versions before 0.63.1 that use IASContextProvider, which is registered by default via bootstrap(app). Fixed in 0.63.1.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 0.63.1
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Published
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The SAP Cloud SDK for Python has a flaw where its IAS context provider accepts identity claims from a JWT without checking the token's signature. A remote attacker without logging in can forge a token naming another tenant and user, so that spoofed identity is trusted in telemetry, logs, audit events, and tenant routing, which affects integrity.
Read the original description
The SAP Cloud SDK for Python contains an improper cryptographic signature verification vulnerability (CWE-347) in IASContextProvider, the runtime-context provider registered by default via bootstrap(app).IASContextProvider extracted the app_tid, sap_gtid and user_uuid claims from the IAS JWT in the Authorization header using an unverified decoder and wrote them into the request-scoped RuntimeContext without validating the token signature. A remote caller could submit a self-signed JWT naming a victim tenant/user; the forged identity then propagated to every consumer of the runtime context:OTel span attributes (sap.tenancy.tenant_id, user.id) via RuntimeContextSpanProcessorlog records via IdentityLogFilteraudit events (tenant_id, user_initiator_id) via AuditClienttenant routing via CBCClientThis completes an earlier remediation that fixed the same unverified pattern in StarletteIASTelemetryMiddleware but did not cover IASContextProvider.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 0.63.1.
Workaround: Enforce JWT signature verification at ingress before the request reaches the SDK, or supply an explicit verified TokenVerifier to the provider.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- SAP_SE SAP Cloud SDK for Python
fixed in 0.63.1
Evidence 2
- Advisory
- Link
Corrections
None so far.
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Questions about CVE-2026-109799
Is CVE-2026-109799 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
IASContextProvider accepts a JWT without checking its signature, so a remote caller can submit a self-signed token naming a victim tenant or user. That forged identity then propagates to OpenTelemetry spans, log records, audit events and tenant routing.Source: github.com
Which versions are affected by CVE-2026-109799?
SAP Cloud SDK for Python: before 0.63.1.Source: cve.now feed data
Am I affected, and how do I check?
Versions of sap-cloud-sdk for Python installed from pip before 0.63.1 are affected when IASContextProvider is in use, which happens by default through bootstrap(app). To check, run pip show sap-cloud-sdk and compare the reported version with 0.63.1.Source: github.com
How do I fix CVE-2026-109799?
Upgrade sap-cloud-sdk for Python to 0.63.1 or later, which makes IASContextProvider verify the JWT signature through a JWKS-backed IASVerifier. If the upgrade cannot happen yet, enforce JWT signature verification at ingress before requests reach the SDK, or supply an explicit verified TokenVerifier to the provider.Source: github.com