CVE intelligence and bounded remediation

CVE-2019-25714 — Seeyon OA A8 security vulnerability

Critical CVSS 9.3

Seeyon OA A8 contains an unauthenticated arbitrary file write vulnerability in the /seeyon/htmlofficeservlet endpoint that allows remote attackers to write arbitrary files to the web application root by sending specially crafted POST requests with custom base64-encoded payloads. Attackers can write JSP webshells to the web root and execute them through the web server to achieve arbitrary OS command execution with web server privileges. Exploitation evidence was first observed by the Shadowserver Foundation on 2021-03-26 (UTC).

Severity
Critical
CVSS
9.3 (4.0)
Published
2026-04-21
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-434

Affected products

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Matched remediation archetype

Path traversal, unsafe upload, and file handling

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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