CVE-2026-81938 Grafana Mimir - Information Disclosure

Grafana Mimir < 3.1.7 and < 3.2.2 contains a file read vulnerability caused by insufficient validation of http_headers.<name>.files and basic_auth.username_file in Alertmanager tenant configurations, letting tenants with config upload permission read arbitrary files on the Alertmanager host by directing receivers to attacker-controlled servers.

CVSS base score 7.7 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
View the NVD record ↗

Details

Type
Information Disclosure
Impact
File System Read, Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Published
2 November 2026
Updated
3 November 2026
Weakness
CWE-22

Vendor fix

Upgrade to Mimir 3.1.7, 3.2.2 or GEM 2.17.20 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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