Analysis
CVE-2026-108860 sits one level below 'Ships Without Auth': the authentication gate works as designed, but the HMAC secret it validates against is committed in the framework's own configuration file. No patched version is published.
The signing key for the framework’s login tokens sits in the starter template’s configuration file, in the repository, in plain text. This flaw, identified as CVE-2026-108860, represents a failure of trust-through-defaults at the supply-chain layer. A framework that ships its trust root as a source constant provides every agent built on its starter with a pre-baked forgery path.
This issue sits one level below the pattern described in our previous analysis, Ships Without Auth. In those cases, the control planes lacked authentication entirely. Here, the authentication gate exists and functions as designed. The vulnerability is that the key it trusts is public. The framework ships with a sample configuration file that includes a static HMAC secret used for signing JSON Web Tokens.
BotSharp through 5.2.0 contains an authentication bypass vulnerability that allows unauthenticated remote attackers to forge bearer tokens using the hard-coded Jwt:Key in WebStarter appsettings.json. Attackers can sign tokens with the committed HMAC secret and fixed botsharp issuer and audience to impersonate any known user, including administrators, on Authorize-protected API routes.
This description comes from the advisory record published on Oct 11, 2026. The vulnerability is classified as CWE-321, Use of Hard-coded Cryptographic Key. The GitHub Advisory Database record status is Unreviewed, with affected and patched versions listed as Unknown. On the NVD page, the CVSS metric source is labeled VulnCheck, and NVD analysis is not yet provided. The advisory record serves a CVSS v4.0 score of 9.3.
The mechanism of the attack is straightforward. The signing key is public in the source control repository. Anyone can sign a valid HMAC token using this key. The issuer and audience are fixed constants set to botsharp. API routes protected by the framework’s authorization attribute accept these tokens. Because the token validates cryptographically against the committed key, no authentication system is ever consulted. An attacker can impersonate any user, including administrators, without triggering a login event.
Primary evidence is visible in lines 16 through 20 of the WebStarter appsettings.json file. This configuration block contains the 64-character HMAC secret. It is part of the sample settings file shipped in the framework source tree. It sits alongside LLM provider entries and empty OAuth secret blocks. The secret value is not printed here. Its role is the root of trust.
The version scope of this vulnerability is defined by the advisory description as through 5.2.0. While the VulnCheck advisory provides additional context, the VulnCheck CPE line reads BotSharp <= 5.2.0 with vendor SciSharp. The VulnCheck advisory credits disclosure to the researcher handle hieuPenguinnn. This piece asserts no CISA KEV status. The record asserts no exploitation in the wild. The EPSS score of 0.476 percent is a prediction metric.
For builders and defenders, the implication is mechanical. A starter template’s sample configuration becomes production code the moment a developer fails to change it. The only deployment-level check that matters is whether the running Jwt:Key matches the value committed in the repository. If the value remains unchanged, the authentication gate is effectively bypassed. The running Jwt:Key either matches the committed value or it does not.
Heath Callahan works for Forkast.
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