EUVD-2026-50207
GHSA-4c56-c2ph-pp8x
Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/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
AV:N because ATS is network-facing; AC:H for required connection coalescing precondition; C:L/I:L for partial traffic misdirection with no availability impact.
Primary rating from Vendor (apache).
CVSS VectorVendor: apache
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/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
Lifecycle Timeline
3DescriptionCVE.org
Apache Traffic Server reuses multiplexed HTTP/2 origin connections without verifying the server certificate covers the new request hostname.
This issue affects Apache Traffic Server: from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3.
Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
AnalysisAI
Improper TLS certificate validation in Apache Traffic Server (ATS) versions 9.0.0-9.2.14 and 10.0.0-10.1.3 allows multiplexed HTTP/2 origin connections to be reused for requests targeting hostnames not covered by the existing connection's server certificate. When ATS coalesces HTTP/2 connections to origin servers, it omits the check confirming the server certificate's Subject Alternative Names cover the new request's hostname, meaning traffic may be silently routed over a connection authenticated for a different host. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that ATS has an active, multiplexed HTTP/2 connection to an origin server whose IP address is also associated with a different target hostname in the same proxy environment - specifically, the connection coalescing optimization must be triggered, meaning both hostnames must resolve to the same origin IP and port. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 4.8 (Medium) with vector AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N accurately captures the constrained exploitability: AC:H reflects that connection coalescing must already be active and the attacker must control or influence a hostname sharing an origin IP with the target, a non-trivial prerequisite. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker operating or influencing two origin hostnames (e.g., attacker-controlled.example and target.example) that resolve to the same IP address sends requests through a vulnerable ATS instance. Because an existing HTTP/2 connection to that IP is already open and ATS skips certificate hostname validation before coalescing, ATS routes the request for target.example over the TLS session established for attacker-controlled.example. … |
| Remediation | The primary fix is to upgrade Apache Traffic Server to version 9.2.15 (for the 9.x branch) or 10.1.4 (for the 10.x branch), both of which enforce certificate hostname validation before reusing multiplexed HTTP/2 connections to origin servers, per the Apache advisory at https://lists.apache.org/thread/5prl9glcm9g2swnq9hqxvnokylm1gr6d. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-295 – Improper Certificate Validation
View allSame technique Information Disclosure
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External POC / Exploit Code
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