CVE-2026-87011Public exploitNetwork attack vector

Unauthenticated service stall via uncached OIDC fetches

Published Sep 9, 2026 · Updated Sep 9, 2026

Resource exhaustion in Open WebUI 0.9.0 through 0.11.0 allows remote attackers to stall the server through back-channel logout. The POST /oauth/backchannel-logout handler fetches uncached OIDC discovery metadata and signing keys before token validation, while a blocking key lookup stalls the async event loop. Exploitation requires back-channel logout and an OIDC provider to be configured; no account is needed, and the resulting interruption is instance-wide on the default single-worker setup.

CVSS severity7.5
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Open WebUI 0.9.0 through 0.11.0 allows remote attackers to stall the server through back-channel logout. The POST /oauth/backchannel-logout handler fetches uncached OIDC discovery metadata and signing keys before token validation, while a blocking key lookup stalls the async event loop. Exploitation requires back-channel logout and an OIDC provider to be configured; no account is needed, and the resulting interruption is instance-wide on the default single-worker setup.

The record

CVE
CVE-2026-87011
Published
Sep 9, 2026
Updated
Sep 9, 2026
Vendor
Open WebUI
Product
Open WebUI
Classifications
CWE-405, CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.9.0, < 0.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Open WebUI · Open WebUIversion=>= 0.9.0, < 0.11.1

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-405Asymmetric Resource Consumption (Amplification)
CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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