Answer in brief
CVE-2026-85751 records a Unknown severity vulnerability in Mailu: Authentication bypass in header-based proxy authentication via spoofable `X-Forwarded-By` trust. The current sources do not mark it as known exploited. The current feed maps Mailu/helm-charts (generic), Mailu/Mailu (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Mailu/helm-charts (generic), Mailu/Mailu (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Mailu/helm-chartsgeneric | < 2.7.3 | Not reported |
| Mailu/Mailugeneric | >= 2.0.0, < 2024.06.55 | Not reported |
Published upstream
Sep 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 21, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 21, 2026
Mailu is a mail server distributed as a set of Docker images. From Mailu 2.0 until 2024.06.55 and prior to Mailu helm-charts 2.7.3, deployments with PROXY_AUTH_WHITELIST configured but REAL_IP_HEADER unset trusted a client-controlled X-Forwarded-By header for header-based proxy authentication. The proxy_hide_header directive in the nginx template at core/nginx/conf/proxy.conf hid the header from upstream responses but did not overwrite the incoming request value in this configuration. An unauthenticated remote attacker could therefore spoof the trusted proxy identity and bypass authentication. This issue is fixed in Mailu 2024.06.55 and Mailu helm-charts 2.7.3.
Quoted source text, attributed separately from HOL analysis.