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No exploitation reportedAwaiting NVD analysis

CVE-2026-81938

Arbitrary file read via Alertmanager receiver configuration in Grafana Mimir

No exploitation reported by the sources we read.

  • Published2026-11-02
  • WeaknessCWE-22

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Grafana Mimir's Alertmanager rejects tenant-supplied receiver configurations that reference local files, but the check did not cover two HTTP client settings: http_headers.<name>.files and basic_auth.username_file. A tenant permitted to upload an Alertmanager configuration could point these fields at any file readable by the Alertmanager process. When a notification was sent, Alertmanager read the file and put its contents in a header of the outgoing request. By directing the receiver at a server they control, the tenant could read files from the Alertmanager host, such as credentials and configuration. Exploitation requires permission to write the tenant's Alertmanager configuration. Grafana Enterprise Metrics (GEM), which is built on Mimir, is also affected. The issue is fixed in Mimir 3.1.7 and 3.2.2 and in GEM 2.17.20. GEM 2.11 through 2.16 will not receive a fix; users on those versions should upgrade to 2.17.20 or later.

Timeline

dates in UTC
  1. 2026-11-0218:23CVE publishedCNA

Observed activity

isMalicious corpus · updated 2026-11-02 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-81938?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-81938?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Products declared by the CNA

As GRAFANA, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • Grafana Enterprise Metrics (GEM)other versions: not affected
    Affected
    • ≥ 2.11.0, ≤ 2.16.2no fix statedsemver
    • ≥ 2.17.0, < 2.17.20fixed in 2.17.20semver
  • Grafana Mimirother versions: not affected
    Affected
    • ≥ 3.0.4, < 3.1.7fixed in 3.1.7semver
    • ≥ 3.2.0, < 3.2.2fixed in 3.2.2semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-02

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-81938 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

  • NVDCVE recordread 2026-11-02
  • CISA-ADPSSVC decisionnone2026-11-02
  • OpenCVESSVC decisionnone—
  • CNACVSS 3.17.72026-11-02
  • CNAweakness (CWE)CWE-222026-11-02

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Published
2026-11-02
Last Modified
2026-11-02
NVD status
Received

Frequently asked questions

What is CVE-2026-81938?

Grafana Mimir's Alertmanager rejects tenant-supplied receiver configurations that reference local files, but the check did not cover two HTTP client settings: http_headers.<name>.files and basic_auth.username_file. A tenant permitted to upload an Alertmanager configuration could point these fields at any file readable by the Alertmanager process. When a notification was sent, Alertmanager read the file and put its contents in a header of the outgoing request. By directing the receiver at a server they control, the tenant could read files from the Alertmanager host, such as credentials and configuration. Exploitation requires permission to write the tenant's Alertmanager configuration. Grafana Enterprise Metrics (GEM), which is built on Mimir, is also affected. The issue is fixed in Mimir 3.1.7 and 3.2.2 and in GEM 2.17.20. GEM 2.11 through 2.16 will not receive a fix; users on those versions should upgrade to 2.17.20 or later.

Is CVE-2026-81938 actively exploited?

Active exploitation of CVE-2026-81938 has not been confirmed.

What is the CVSS score for CVE-2026-81938?

CVE-2026-81938 has a CVSS v3 base score of 7.7 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N.

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