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.
CVE-2026-85751
“—” beside the score: it is equal to the CVSS score beside it.
This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (46th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Also known asEUVD-2026-83975 (ENISA EUVD)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 9.8
- EG Score
- 9.8CRITICALmedium confidence
- EG Risk
- 59EG Risk 59/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity98% × 45%Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.6% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.6%
- EPSS %ILE
- 46th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
September 21, 2026
Last Modified
September 24, 2026
Advisory Details (6)
Auto-updated Oct 31, 2026Authentication bypass in header-based proxy authentication via spoofable `X-Forwarded-By` trust · Advisory · Mailu/Mailu · GitHub
https://github.com/Mailu/Mailu/security/advisories/GHSA-rfhj-4wcq-74xg2024.06.55
Patch available: Mailu/Mailu 2024.06.55
https://github.com/Mailu/Mailu/releases/tag/2024.06.55Ensure we set X-Forwarded-By (backport #4070)
Patch available: Mailu/Mailu 2024.06.55 (PR #4071 merged 2026-07-18)
https://github.com/Mailu/Mailu/pull/4071Ensure we set X-Forwarded-By
Fix merged in Mailu/Mailu PR #4070 on 2026-07-18 — awaiting tagged release
https://github.com/Mailu/Mailu/pull/4070commit ff4003d04575 (Mailu/Mailu)
Patch available: Mailu/Mailu 2024.06.55 (contains commit ff4003d04575)
https://github.com/Mailu/Mailu/commit/ff4003d045753013470945336448dbd790cac778commit dffa97cbd889 (Mailu/Mailu)
Fix landed in Mailu/Mailu commit dffa97cbd889 — awaiting tagged release
https://github.com/Mailu/Mailu/commit/dffa97cbd889ab208246372ce9c86e99abb27ae9Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 13× in last 7d / 63× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-11-01 12:58 UTCEG score recompute
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-31 14:21 UTCEG score recompute
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-29 17:05 UTCEG score recompute
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-28 18:27 UTCEG score recompute
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-27 19:43 UTCEG score recompute
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-26 21:05 UTCEG score recompute
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-25 20:23 UTCEG score recompute
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-10-25 13:55 UTCEG score recompute
- 2026-10-24 21:45 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-23 23:07 UTCEG score recompute
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-23 00:07 UTCEG score recompute
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-22 01:15 UTCEG score recompute
- 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-21 02:36 UTCEG score recompute
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- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-20 03:48 UTCEG score recompute
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-19 04:38 UTCEG score recompute
- 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-18 03:05 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-17 05:59 UTCEG score recompute
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-16 07:06 UTCEG score recompute
- 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-15 05:52 UTCEG score recompute
- 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-10-14 01:29 UTCEG score recompute
- 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-12 21:41 UTCEG score recompute
- 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-12 14:52 UTCEG score recompute
- 2026-10-11 19:17 UTCEG score recompute
- 2026-10-11 16:34 UTCEG score recompute
- 2026-10-11 13:51 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-10 22:38 UTCEG score recompute
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-09 20:21 UTCEG score recompute
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-08 17:19 UTCEG score recompute
- 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-08 01:56 UTCEG score recompute
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-06 16:22 UTCEG score recompute
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-05 18:02 UTCEG score recompute
- 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-04 23:27 UTCEG score recompute
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-03 17:50 UTCEG score recompute
- 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-02 19:32 UTCEG score recompute
- 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-10-01 20:56 UTCEG score recompute
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-30 15:17 UTCEG score recompute
- 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-29 18:18 UTCEG score recompute
- 2026-09-28 23:19 UTCEG score recompute
- 2026-09-28 15:36 UTCEG score recompute
- 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-27 17:11 UTCEG score recompute
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-26 18:46 UTCEG score recompute
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 44th percentile
- 2026-09-26 03:51 UTCEG score recompute
- 2026-09-24 14:11 UTCEG score recompute
- 2026-09-24 14:04 UTCEPSS rescoreEPSS 1.1% · 63rd percentile
- 2026-09-23 19:08 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-22 16:42 UTCEG score recompute
- 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.6% · 45th percentile
- 2026-09-21 16:24 UTCEG score recompute
- 2026-09-21 15:45 UTCEG score recomputeFirst assessed: 9.8 CRITICAL
- 2026-09-21 15:45 UTCMITRE cvelistV5first tracked
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Frequently asked(5)
What is CVE-2026-85751?
When was the CVE record for CVE-2026-85751 published?
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What is the CVSS score of CVE-2026-85751?
How do I remediate CVE-2026-85751?
Dependency Blast Radius
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