Bearer-token disclosure via poisoned Teams serviceUrl
Published Jun 1, 2026 · Updated Jun 1, 2026
SSRF in nanobot's Microsoft Teams handler before 0.2.1 allows remote attackers to exfiltrate Bot Framework bearer tokens. The handler stores an inbound activity's unrestricted serviceUrl, then uses it as the base for a later reply carrying an Authorization bearer token. Exploitation requires a reachable Teams webhook with inbound authentication disabled, bypassed, or misconfigured; the default validation setting normally blocks forged activities.
Summary
What happened
SSRF in nanobot's Microsoft Teams handler before 0.2.1 allows remote attackers to exfiltrate Bot Framework bearer tokens. The handler stores an inbound activity's unrestricted serviceUrl, then uses it as the base for a later reply carrying an Authorization bearer token. Exploitation requires a reachable Teams webhook with inbound authentication disabled, bypassed, or misconfigured; the default validation setting normally blocks forged activities.
The record
- CVE
- CVE-2026-49139
- Published
- Jun 1, 2026
- Updated
- Jun 1, 2026
- Vendor
- Data Intelligence Lab @ HKU
- Product
- nanobot
- Classifications
- CWE-918, T1190, T1528
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 1, 2026CVE publishedPublication date reported by the CVE source.
- Jun 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.2.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Microsoft Teams serviceUrl poisoning safe reproductionproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo