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Vulnerability record · CVE-2026-56676 · published 10 July 2026

CVE-2026-56676: TOCTOU race condition vulnerability

9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. An authenticated attacker with access to the LLM proxy can use a vision-capable model and an attacker-controlled DNS name that first resolves to a public IP and then rebinds to an internal address, allowing server-side requests to internal-only HTTP services. This issue is fixed in version 0.5.2.

7.4 CVSS 3.1 High EPSS 0.26% · top 84.1% CWE-367 · TOCTOU race conditionCWE-918 · Server-side request forgery (SSRF) Deferred
7.4CVSS 3.1 base score
0.26%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
13 Jul 2026Last modified by NVD

Description

9Router is an AI router & token saver. Prior to 0.5.2, 9router validates image URLs by resolving the host before fetching, but open-sse/translator/concerns/image.js performs the later server-side image fetch with a separate DNS resolution. An authenticated attacker with access to the LLM proxy can use a vision-capable model and an attacker-controlled DNS name that first resolves to a public IP and then rebinds to an internal address, allowing server-side requests to internal-only HTTP services. This issue is fixed in version 0.5.2.

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

References

LinkTags
https://github.com/decolua/9router/commit/c7d07448c58bec1200741de0b73305b860416b82
https://github.com/decolua/9router/releases/tag/v0.5.2
https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx
https://github.com/decolua/9router/security/advisories/GHSA-cmhj-wh2f-9cgx

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Source: NIST National Vulnerability Database (record CVE-2026-56676), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.