Vulnerability · Published Oct 11, 2026 · Assigned by VulnCheck

CVE-2026-108860BotSharp through 5.2.0 Authentication Bypass via Hard-Coded JWT Signing Key

Critical 9.1

In plain English

A critical-severity security flaw in BotSharp from SciSharp. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities).

Severity (CVSS 3.1)9.1Critical

Exploit odds (30 days)0.5%top 58.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
SciSharp	BotSharp	0 – through 5.2.0

Weakness: CWE-321 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/scisharp-botsharp-public-jwt-signing-key third-party-advisory
https://github.com/SciSharp/BotSharp/blob/a11ee0317cab5c619df1cb5d0c4fc39d1b6e30b4/src/WebStarter/appsettings.json#L16-L20 technical-description
https://github.com/SciSharp/BotSharp/blob/a11ee0317cab5c619df1cb5d0c4fc39d1b6e30b4/src/Infrastructure/BotSharp.OpenAPI/BotSharpOpenApiExtensions.cs#L46-L57 technical-description
https://github.com/SciSharp/BotSharp product
VulnCheck Advisory: BotSharp through 5.2.0 Authentication Bypass via Hard-Coded JWT Signing Key third-party-advisory