HighVulnerabilityLLM-specific

CVE-2026-82639: NextChat improper URL validation in proxy endpoint exposes OpenAI API key

Source: NVD(opens in a new tab)
Identifier: CVE-2026-82639
Published: August 30, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.5%

Summary

NextChat versions 2.15.8 through 2.16.1 contain an improper URL validation flaw in the proxy endpoint. The x-base-url header is checked with substring matching rather than hostname parsing, so any URL containing 'api.openai.com' passes validation and receives the server's credentials in the Authorization header, allowing an attacker to obtain the server's OpenAI API key.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Details

Scores and exploitation

CVSS score: 7.5(high)
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack vector: network
Attack complexity: low
Privileges required: none
User interaction: none
EPSS: 0.5%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 4, 2026.
Disclosure date: August 30, 2026

Weaknesses and techniques

Weakness (CWE): CWE-20

Affected

Vendors: OpenAI

Classification

Attack type: Other
Attack sophistication: Trivial
AI component targeted: API
Impact: Confidentiality
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-82639

First tracked: August 30, 2026 at 02:08 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 93% (self-assessed)

Summary

Mitigation

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