CVE-2026-87011: open webui DoS — Exploit & Fix

Description

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.0 until 0.11.1, the unauthenticated POST /oauth/backchannel-logout handler in backend/open_webui/utils/oauth.py fetched the OIDC discovery document and signing keys before validating a submitted logout token. Each request repeated uncached network fetches, and the signing-key lookup blocked the async event loop, so requests carrying invalid tokens could stall the single-worker instance and amplify traffic to the identity provider when ENABLE_OAUTH_BACKCHANNEL_LOGOUT was enabled. This issue is fixed in version 0.11.1.

Is your site exposed to CVE-2026-87011?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0064

Probability of exploitation

0.49%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-405 CWE-405

CWE-770 CWE-770

Affected Products

Vendor	Product	Versions
openwebui	open_webui	0.9.0 — 0.11.1

References

Advisories & Patches

https://github.com/open-webui/open-webui/commit/aeda6ff13a25d3b3ba1b303609f35382db22142c https://github.com/open-webui/open-webui/security/advisories/GHSA-3g9q-v48f-hh9w https://github.com/open-webui/open-webui/security/advisories/GHSA-3g9q-v48f-hh9w

Exploits

https://github.com/open-webui/open-webui/security/advisories/GHSA-3g9q-v48f-hh9w https://github.com/open-webui/open-webui/security/advisories/GHSA-3g9q-v48f-hh9w

Other References

https://github.com/open-webui/open-webui/releases/tag/v0.11.1

Frequently Asked Questions

What is CVE-2026-87011? +

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.0 until 0.11.1, the unauthenticated POST /oauth/backchannel-logout handler in backend/open_webui/utils/oauth.py fetched the OIDC discovery document and signing keys before validating a submitted logout token. Each request repeated uncached network fetches, and the signing-key lookup blocked the async event loop, so requests carrying invalid tokens could stall the single-worker instance and amplify traffic to the identity provider when ENABLE_OAUTH_BACKCHANNEL_LOGOUT was enabled. This issue is fixed in version 0.11.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-87011? +

CVE-2026-87011 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0064, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-87011? +

CVE-2026-87011 affects products from openwebui, specifically: open_webui. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-87011? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-118764

minimatch is a minimal matching utility for converting glob expressions into JavaScript RegExp objects. Prior to 11.0.1, src/index.ts implements firstPhasePreProcess() …

CVE-2026-85783

Crypt::Age versions before 0.004 for Perl allow CPU exhaustion via an unbounded number of recipient stanzas, each costing an X25519 …

CVE-2026-119207

pypdf is a free and open-source pure-python PDF library. Prior to 6.21.3, pypdf can consume excessive memory when strict mode …

CVE-2025-32394

AutoGPT is a workflow automation platform for creating, deploying, and managing continuous artificial intelligence agents. Prior to 0.6.32, there is …

CVE-2026-68531

Concrete CMS 9 before 9.5.3 did not escape SQL LIKE wildcard characters in the keyword search filters used by the …

CVE-2026-110676

Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum. With …