EUVD-2026-41654
GHSA-pxqg-8rwp-q2x2
Severity by source
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/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 vector with authenticated low-privilege access and high complexity required; impact is confidentiality-only at low severity with no scope change.
Primary rating from Vendor (vuldb).
CVSS VectorVendor: vuldb
CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/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
1DescriptionCVE.org
A security vulnerability has been detected in NousResearch hermes-agent up to 2026.4.30. Affected is the function GatewayStreamConsumer._filter_and_accumulate of the file gateway/stream_consumer.py of the component Streaming Reasoning Tag Filter. The manipulation leads to improper handling of case sensitivity. The attack may be initiated remotely. The attack's complexity is rated as high. The exploitability is told to be difficult. The exploit has been disclosed publicly and may be used. The project decided to not implement a dedicated fix: "[T]he analysis and the fix are both sound. It just lands below the bar for the maintenance cost of a duplicated scrub path."
AnalysisAI
Case-sensitivity bypass in NousResearch hermes-agent through version 2026.4.30 allows authenticated remote attackers to leak limited reasoning content that should have been scrubbed by the Streaming Reasoning Tag Filter. The vulnerability resides in GatewayStreamConsumer._filter_and_accumulate within gateway/stream_consumer.py, where tag matching fails to account for case variations, permitting reasoning tokens to escape filtration. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires authenticated access with at minimum low-privilege credentials (PR:L in the CVSS 4.0 vector) - unauthenticated exploitation is not supported by the available data. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The aggregate risk picture is low. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An authenticated user with network access to the hermes-agent streaming endpoint crafts requests that inject reasoning tags using non-standard casing variations. When the streamed response is processed by `_filter_and_accumulate`, the case-sensitive filter fails to match and scrub the reasoning tokens, causing the internal reasoning content to be returned in the output stream. … |
| Remediation | No vendor-released patch is planned. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-178 – Improper Handling of Case Sensitivity
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External POC / Exploit Code
Leaving vuln.today