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01 Record

CVE-2026-39858

Traefik: Forwarded alias spoofing top pre-auth decision bypass

HighPUBLISHEDCNA: GitHub_M
CNA base score7.8 CVSS v4.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
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02 Description

Traefik: Forwarded alias spoofing top pre-auth decision bypass

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 ImpactpartialSuccessful exploitation gives limited 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
0.47% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 41.0% of scored records. A rank, not a probability.
NVD base score
7.8 (CVSS v4.0), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD analysis status
Modified. NVD last modified this record on 2026-07-15.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

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
2026-04-30 20:26Z6 MO AGO
Last updated
2026-07-15 01:01Z3 MO AGO
Reserved
2026-04-07
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
High (CVSS 7.8)
CNA CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
Weaknesses
  • CWE-290Authentication Bypass by SpoofingBase
  • CWE-306Missing Authentication for Critical FunctionBase
  • CWE-289Authentication Bypass by Alternate NameBase
Data version
5.2
Document digest
2f9626c707bc3a8838605bdcebefafc06f0dc54c852c5a5985b2227cc364eec9

05 Affected products

VendorProductVersionsPlatforms
traefiktraefik< 2.11.43, >= 3.0.0-beta1, < 3.6.14, >= 3.7.0-ea.1, < 3.7.0-rc.2—

06 References