CVE-2026-49139
CVE-2026-49139 is a high-severity vulnerability with a CVSS 4.0 base score of 7.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.
Key facts
- Severity: High (CVSS 4.0 base score 7.0)
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-33759
- Weakness: CWE-918
- Published:
- Last modified:
Description
Nanobot prior to version 0.2.1 contains a server-side request forgery vulnerability in the Microsoft Teams channel handler that allows remote attackers to exfiltrate Bot Framework bearer tokens by supplying a forged activity with an attacker-controlled serviceUrl value. Attackers can poison the stored conversation reference by sending a crafted inbound activity to the Teams webhook, causing subsequent bot replies to transmit token-bearing Authorization header requests to an attacker-controlled host.
Frequently asked questions
- What is CVE-2026-49139?
- Nanobot prior to version 0.2.1 contains a server-side request forgery vulnerability in the Microsoft Teams channel handler that allows remote attackers to exfiltrate Bot Framework bearer tokens by supplying a forged activity with an attacker-controlled serviceUrl value. Attackers can poison the stored conversation reference by sending a crafted inbound activity to the Teams webhook, causing subsequent bot replies to transmit token-bearing Authorization header requests to an attacker-controlled host.
- How severe is CVE-2026-49139?
- CVE-2026-49139 has a CVSS 4.0 base score of 7.0, rated high severity.
- Is CVE-2026-49139 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-49139?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-49139 have an EU (EUVD) identifier?
- Yes. CVE-2026-49139 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33759.
- When was CVE-2026-49139 published?
- CVE-2026-49139 was published on 2026-06-01 and last updated on 2026-06-17.
References
- https://github.com/HKUDS/nanobot/commit/232df45126bcf0f8fccd123d73714f202c8e8612
- https://github.com/HKUDS/nanobot/pull/4047
- https://github.com/HKUDS/nanobot/releases/tag/v0.2.1
- https://www.vulncheck.com/advisories/nanobot-ssrf-via-microsoft-teams-channel-serviceurl-poisoning
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