EUVD-2026-50235
GHSA-c6fq-3mhw-8g4j
Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/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
Network-accessible HTTP/2 endpoint requires no auth, but encode failure triggering demands specific conditions (AC:H); only connection-scoped integrity and availability are impacted.
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:N/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 updates the HTTP/2 HPACK dynamic table before confirming the header block encoded successfully, so an encode failure leaves the encoder out of sync with the peer decoder and corrupts subsequent header blocks on the connection.
This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, 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
HTTP/2 HPACK dynamic table desynchronization in Apache Traffic Server (versions 8.0.0-8.1.9, 9.0.0-9.2.14, and 10.0.0-10.1.3) exposes a premature-state-update flaw in header compression logic. An unauthenticated remote attacker can trigger an HPACK encode failure, leaving the server's encoder table out of sync with the peer decoder's table and corrupting all subsequent header blocks transmitted on that HTTP/2 connection. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | HTTP/2 must be enabled on the Apache Traffic Server instance - the HPACK dynamic table logic is only active for HTTP/2 connections and has no equivalent in HTTP/1.1 processing. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS vector (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L) yields a Medium score of 4.8, which is broadly consistent with the vulnerability's realistic impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker establishes an HTTP/2 connection to a vulnerable Apache Traffic Server instance and sends crafted header blocks engineered to trigger an HPACK encode failure mid-operation. Because ATS has already updated its dynamic table before detecting the failure, subsequent headers on the connection are encoded against a diverged table state and are decoded incorrectly by the peer. … |
| Remediation | The primary remediation is to upgrade Apache Traffic Server to version 9.2.15 or 10.1.4, both of which contain the vendor-confirmed fix. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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