CVE-2026-35583

The configuration API endpoint (/api/configuration/{name}) validated
configuration names using a blacklist approach that checked for \, /, ..,
and trailing .. This could potentially be bypassed using URL-encoded variants,
double-encoding, or Unicode normalization to achieve path traversal and read
configuration files outside the intended directory.

Details

Vulnerable code, Configs.java (line 126)

protected static String validate(String config) {
    if (StringUtils.isBlank(config) || config.contains("\\") || config.contains("/")
        || config.contains("..") || config.endsWith(".")) {
        throw new IllegalArgumentException("Invalid config name: " + config);
    }
    return Strings.CS.appendIfMissing(config.trim(), CONFIG_FILE_ENDING);
}

Weakness

The blacklist blocked literal \, /, .., and trailing . but could
potentially miss:

• URL-encoded variants (%2e%2e%2f) if decoded after validation
• Double-encoded sequences (%252e%252e%252f)
• Unicode normalization bypasses
• The approach relies on string matching rather than canonical path resolution

Workarounds

If upgrading is not immediately possible, deploy a reverse proxy or WAF rule
that rejects requests to /api/configuration/ containing encoded path traversal
sequences.

References

• PR #1292, validate config name with an allowlist
• Original report: GHSA-wjqm-p579-x3ww

• Potential read access to configuration files outside the intended config
  directory
• Information disclosure of sensitive configuration values

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-35583 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.39.0); upgrading removes the vulnerable code path.

Kodem intelligence

Fixed in PR #1292,
merged into release 8.39.0.

The blacklist was replaced with an allowlist regex that only permits characters
matching ^[a-zA-Z0-9._-]+$:

protected static final Pattern VALID_CONFIG_NAME = Pattern.compile("^[a-zA-Z0-9._-]+$");

protected static String validate(String config) {
    if (!VALID_CONFIG_NAME.matcher(config).matches() || config.contains("..") || config.endsWith(".")) {
        throw new IllegalArgumentException("Invalid config name: " + config);
    }
    return Strings.CS.appendIfMissing(config.trim(), CONFIG_FILE_ENDING);
}

This ensures that any character outside the allowed set, including encoded
slashes, percent signs, and Unicode sequences, is rejected before the config
name reaches the filesystem.

Tests were added to verify that URL-encoded (%2e%2e%2f), double-encoded
(%252e%252e%252f), and Unicode (U+002F) traversal attempts are blocked.

1. What is CVE-2026-35583? CVE-2026-35583 is a medium-severity path traversal vulnerability in gov.nsa.emissary:emissary (maven), affecting versions < 8.39.0. It is fixed in 8.39.0. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-35583? CVE-2026-35583 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of gov.nsa.emissary:emissary are affected by CVE-2026-35583? gov.nsa.emissary:emissary (maven) versions < 8.39.0 is affected.
4. Is there a fix for CVE-2026-35583? Yes. CVE-2026-35583 is fixed in 8.39.0. Upgrade to this version or later.
5. Is CVE-2026-35583 exploitable, and should I be worried? Whether CVE-2026-35583 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-35583 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-35583? Upgrade gov.nsa.emissary:emissary to 8.39.0 or later.