CVE-2026-27480: Static web server Static Web Server Affected By Vulnerability

MODERATE
Advisory Identifier: GHSA-qhp6-635j-x7r2
Share
CVSS 5.3
CWE-204
Published
Advisory Summary

CVE-2026-27480 is a MODERATE (CVSS 5.3) static web server affected by vulnerability (CWE-204: Observable Response Discrepancy) affecting Static web server libraries in the crates.io ecosystem. The issue involves static web server affected by timing-based username enumeration in basic authentication due to early response on invalid usernames. Remediation is available by upgrading affected packages to version 2.41.0.

CVE-2026-27480 at a Glance

CVE Identifier CVE-2026-27480
GHSA Identifier GHSA-qhp6-635j-x7r2
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-204: Observable Response Discrepancy
Affected Product Static web server
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-27480

To remediate this vulnerability, upgrade all affected Static web server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

static-web-server fixed: 2.41.0 
Upgrade static-web-server to 2.41.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for static-web-server

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-27480, inspect your project dependencies for Static web server:

inspect dependencies for static-web-server

Analyze the terminal output to locate any version of Static web server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.41.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-204: Observable Response Discrepancy, where the product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere. In Static web server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## 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.

CVE-2026-27480 Affected Static web server Versions

1 component(s)
Fixed Versions:
2.41.0
Product / Package Ecosystem Affected Versions Fixed Version
static-web-server
 crates.io
≥ 2.1.0
< 2.41.0
2.41.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/static-web-server/static-web-server/security/advisories/GHSA-qhp6-635j-x7r2
NVD — CVE-2026-27480 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27480
Security Fix Commit FIX COMMIT
https://github.com/static-web-server/static-web-server/commit/7bf0fd425eb10dac9bf9ef5febce12c4dd039ce1
Static web server Source Repository REPOSITORY
https://github.com/static-web-server/static-web-server

Frequently Asked Questions

What is CVE-2026-27480?
CVE-2026-27480 is a security vulnerability in Static web server involving Static Web Server affected by timing-based username enumeration in Basic Authentication due to early response on invalid usernames under CWE-204: Observable Response Discrepancy.
Which Static web server versions are affected?
Affected versions include releases prior to 2.41.0 across affected packages: static-web-server.
What version fixes CVE-2026-27480?
Upgrading to 2.41.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is static-web-server affected?
Yes, static-web-server is affected in releases prior to 2.41.0. Upgrade your dependency to 2.41.0 or later.
What is the CVSS score of CVE-2026-27480?
CVE-2026-27480 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-27480?
CVE-2026-27480 is classified under CWE-204: Observable Response Discrepancy (The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.).
How can I check crates.io dependencies for CVE-2026-27480?
Run the dependency tree command: 'inspect dependencies for static-web-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-qhp6-635j-x7r2",
  "modified" : "2026-02-23T22:28:57Z",
  "published" : "2026-02-20T18:25:27Z",
  "aliases" : [ "CVE-2026-27480" ],
  "summary" : "Static Web Server affected by timing-based username enumeration in Basic Authentication due to early response on invalid usernames",
  "details" : "## Summary\n\nA 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.\n\n## Details\n\nSWS validates the provided username before performing any password verification.\n- **Invalid Username:** The server returns a `401 Unauthorized` response immediately.\n- **Valid Username:** The server proceeds to verify the password (e.g., using `bcrypt`), which introduces a different execution path and measurable timing discrepancy.\n\nThis allows an attacker to distinguish between existing and non-existing accounts by analyzing response times.\n\n## PoC\n\nThe following statistical results were obtained by measuring the mean response time over 100 iterations using a custom Rust script:\n\n| User Type | Average Response Time |\n| :--- | :--- |\n| **Invalid User** | 0.409861 ms |\n| **Valid User** | 0.250925 ms |\n| **Difference** | **~0.158936 ms** |\n\nWhile 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.\n\n## Impact\n\nUsers using the SWS' Basic Authentication feature are primarily impacted.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "static-web-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.1.0"
      }, {
        "fixed" : "2.41.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/static-web-server/static-web-server/security/advisories/GHSA-qhp6-635j-x7r2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27480"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/static-web-server/static-web-server/commit/7bf0fd425eb10dac9bf9ef5febce12c4dd039ce1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/static-web-server/static-web-server"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-204" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-20T18:25:27Z",
    "nvd_published_at" : "2026-02-21T10:16:12Z"
  }
}