What’s Vulnerable › Vulnerabilities

CVE-2026-57522: Bitwarden Server < 2026.5.0 JSON Injection via Webhook Templates

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-25 · updated 2026-10-25
• Weakness: CWE-74

Description

Bitwarden Server before 2026.5.0 contains a JSON injection vulnerability in IntegrationTemplateProcessor.ReplaceTokens(), which substitutes user-controlled values into event-integration templates without JSON encoding. When an organization has configured an event integration whose template references a user-controlled token (such as #ActingUserName# or #UserName#, populated from a member's display name), an authenticated member can set their display name to JSON metacharacters and inject arbitrary key-value pairs into the rendered payloads delivered to webhook, SIEM, Slack, Teams, or Datadog endpoints, making injected fields indistinguishable from legitimate template output.

Affected products

• bitwarden server: before 2026.5.0 — fixed in 2026.5.0

How to fix

Upgrade to a fixed version: bitwarden server 2026.5.0. Check the vendor advisory for mitigations.

References

• https://github.com/bitwarden/server/commit/a26afd18130ef985ede5c97d277820d045185a28
• https://github.com/bitwarden/server/pull/7593
• https://github.com/bitwarden/server/releases/tag/v2026.5.0
• https://sanjokkarki.com.np/blog/bitwarden-webhook-json-injection
• https://www.vulncheck.com/advisories/bitwarden-server-json-injection-via-webhook-templates

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