A vulnerability allowing an unauthenticated attacker to bypass REST API authentication with a forged federation token
Source GCVE Database
Not known to be exploited · CVSS 6.9 Medium · patch available : update Backup for Microsoft 365 when convenient.
Data as of 27 Oct 2026, 20:00 UTC
- Patch
- Available
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 27 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| VeeamBackup for Microsoft 365 | Affected
| Fixed in– |
Description
This vulnerability allows an unauthenticated attacker to bypass REST API authentication by using a forged federation token. The attacker can receive responses from REST API endpoints that do not invoke the Veeam Backup for Microsoft 365 backup service. The vulnerability has a medium severity rating with a CVSS score of 6.9.