CVE-2026-27480

Impact

## Summary A Timing-based username enumeration in Basic Authentication vulnerability due to early response on invalid usernames could allow attackers to identify valid users and focus their efforts on targeted brute-force or credential-stuffing attacks. ## Details SWS validates the provided username before performing any password verification. - **Invalid Username:** The server returns a `401 Unauthorized` response immediately. - **Valid Username:** The server proceeds to verify the password (e.g., using `bcrypt`), which introduces a different execution path and measurable timing discrepancy. This allows an attacker to distinguish between existing and non-existing accounts by analyzing response times. ## PoC The following statistical results were obtained by measuring the mean response time over 100 iterations using a custom Rust script: | User Type | Average Response Time | | :--- | :--- | | **Invalid User** | 0.409861 ms | | **Valid User** | 0.250925 ms | | **Difference** | **~0.158936 ms** | While the valid user responded faster in this specific test environment, the statistically significant gap confirms that the authentication logic does not execute in constant time. ## Impact Users using the SWS' Basic Authentication feature are primarily impacted.

Affected packages

Affected products

Weakness classification

References

• NVD record
• CVE.org record
• GitHub advisory
• https://github.com/static-web-server/static-web-server/commit/7bf0fd425eb10dac9bf9ef5febce12c4dd039ce1
• https://github.com/static-web-server/static-web-server/security/advisories/GHSA-qhp6-635j-x7r2
• https://github.com/advisories/GHSA-qhp6-635j-x7r2
• https://nvd.nist.gov/vuln/detail/CVE-2026-27480