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01 Record

CVE-2026-85751

Mailu: Authentication bypass in header-based proxy authentication via spoofable `X-Forwarded-By` trust

CriticalPUBLISHEDCNA: GitHub_M
CNA base score9.8 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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02 Description

Mailu: Authentication bypass in header-based proxy authentication via spoofable `X-Forwarded-By` trust

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.55% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 46.2% of scored records. A rank, not a probability.
NVD base score
9.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD analysis status
Deferred. NVD last modified this record on 2026-09-24.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-09-21 15:39Z1 MO AGO
Last updated
2026-09-21 17:56Z1 MO AGO
Reserved
2026-09-04
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Critical (CVSS 9.8)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
  • CWE-290Authentication Bypass by SpoofingBase
  • CWE-807Reliance on Untrusted Inputs in a Security DecisionBase
Data version
5.2
Document digest
11d66e9d228a6a9788d891b81a4b9d03cab2ba4d05e239a147dd0576911a376f

05 Affected products

VendorProductVersionsPlatforms
MailuMailu>= 2.0.0, < 2024.06.55—
Mailuhelm-charts< 2.7.3—

06 References