# CVE-2026-74864 — YunoHost-Apps sogo_yhn

> As of 2026-09-30, CVE-2026-74864 is a Critical-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in YunoHost-Apps sogo_yhn, CVSS v4.0 9.3. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-74864, most recently “CVE-2026-74864 / CVE-2026-74865: Authentication bypass in YunoHost-Apps sogo_yhn (SOGo proxy-auth trust)”.

**Last updated:** 2026-09-30

## What is CVE-2026-74864?

sogo_yhn configures SOGo with a parameter that forces the request with HTTP header "x-webobjects-remote-user" to be treated as sent by a verified user without performing password validation. Since Nginx does not strip this header, any client can supply it arbitrarily and gain access as any user, including a privileged user, without providing a password. This issue was fixed in version 5.8.0~ynh9.

The record classifies CVE-2026-74864 under weakness class [CWE-639](https://cwe.mitre.org/data/definitions/639.html). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 1 day ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 9.3 — Critical (derived from score) (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-30

## Is CVE-2026-74864 being exploited?

No public exploitation evidence for CVE-2026-74864 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-09-30. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- **YunoHost-Apps**: sogo_yhn

## How to fix CVE-2026-74864

No vendor patch reference has been recorded for CVE-2026-74864 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-74864

1 tracked threat in the Threadlinqs corpus references CVE-2026-74864, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CVE-2026-74864 / CVE-2026-74865: Authentication bypass in YunoHost-Apps sogo_yhn (SOGo proxy-auth trust)](https://intel.threadlinqs.com/threat/TL-2026-2816) — CRITICAL · 2026-09-30

## Sources

Enriched from CVE.org, NVD. Last verified by Threadlinqs on 2026-10-01. This product uses the NVD API but is not endorsed or certified by the NVD.

**Third-party advisory**

- [cert.pl — third party advisory](https://cert.pl/en/posts/2026/09/CVE-2026-74864)

**Issue tracking and product pages**

- [forum.yunohost.org — issue tracking](https://forum.yunohost.org/t/sogo-critical-vulnerability-fixed-in-5-8-0-ynh9/42699)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-74864
Full detection coverage and IOCs for threats exploiting CVE-2026-74864 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp