CVE-2026-69206: Http4s DigestAuth Allows Replay Of Captured Vulnerability

MODERATE
Advisory Identifier: GHSA-9xww-74xv-gjfp
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CVSS 5.9
CWE-294
Published
Advisory Summary

CVE-2026-69206 is a MODERATE (CVSS 5.9) digestauth allows replay of captured vulnerability (CWE-294: Authentication Bypass by Capture-replay) affecting Http4s libraries in the Maven ecosystem. The issue involves digestauth allows replay of captured requests. Remediation is available by upgrading affected packages to version 0.23.35, 1.0.0-M47.

CVE-2026-69206 at a Glance

CVE Identifier CVE-2026-69206
GHSA Identifier GHSA-9xww-74xv-gjfp
Severity MODERATE
CVSS v3.1 Base Score 5.9
CWE Classification CWE-294: Authentication Bypass by Capture-replay
Affected Product Http4s
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.9

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

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

How to Fix CVE-2026-69206

To remediate this vulnerability, upgrade all affected Http4s dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.http4s:http4s-ember-core_2.12 fixed: 0.23.35 
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-ember-core_2.12</artifactId>
    <version>0.23.35</version>
</dependency>
org.http4s:http4s-ember-core_2.13 fixed: 0.23.35 
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-ember-core_2.13</artifactId>
    <version>0.23.35</version>
</dependency>
org.http4s:http4s-ember-core_3 fixed: 0.23.35 
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-ember-core_3</artifactId>
    <version>0.23.35</version>
</dependency>
org.http4s:http4s-ember-core_2.13 fixed: 1.0.0-M47 
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-ember-core_2.13</artifactId>
    <version>1.0.0-M47</version>
</dependency>
org.http4s:http4s-ember-core_3 fixed: 1.0.0-M47 
<dependency>
    <groupId>org.http4s</groupId>
    <artifactId>http4s-ember-core_3</artifactId>
    <version>1.0.0-M47</version>
</dependency>
Verify Direct and Transitive Dependencies

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

mvn dependency:tree -Dincludes=org.http4s

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-69206, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.http4s

Analyze the terminal output to locate any version of Http4s in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.23.35), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.http4s command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-294: Authentication Bypass by Capture-replay, where a capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). In Http4s, 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

The `DigestAuth` replay defence stores `lastNc + 1` rather than the nonce-count (`nc`) value it just accepted. When a legitimate client sends non-contiguous `nc` values (parallel or retried requests, as browsers do), the server's counter lags behind the highest `nc` seen, and a captured `Authorization` header can be replayed multiple times. ## Impact A passive observer can turn one captured Digest-authenticated request into several replayed authenticated (state-changing) requests, defeating the core replay protection Digest provides over Basic. ## Preconditions - Application uses `DigestAuth`. - Attacker can passively observe at least one legitimate digest request. - Legitimate client emits an `nc` more than one greater than the last, for instance from a parallel or retried request. ## Workarounds - Deploy over TLS so requests cannot be captured.

CVE-2026-69206 Affected Http4s Versions

5 component(s)
Fixed Versions:
0.23.351.0.0-M47
Product / Package Ecosystem Affected Versions Fixed Version
org.http4s:http4s-ember-core_2.12
maven/org.http4s/http4s-ember-core_2.12
Maven
< 0.23.35
0.23.35
org.http4s:http4s-ember-core_2.13
maven/org.http4s/http4s-ember-core_2.13
Maven
< 0.23.35
0.23.35
org.http4s:http4s-ember-core_3
maven/org.http4s/http4s-ember-core_3
Maven
< 0.23.35
0.23.35
org.http4s:http4s-ember-core_2.13
maven/org.http4s/http4s-ember-core_2.13
Maven
≥ 1.0.0-M1
< 1.0.0-M47
1.0.0-M47
org.http4s:http4s-ember-core_3
maven/org.http4s/http4s-ember-core_3
Maven
≥ 1.0.0-M1
< 1.0.0-M47
1.0.0-M47

References

GitHub Advisory / Wiki ADVISORY
https://github.com/http4s/http4s/security/advisories/GHSA-9xww-74xv-gjfp
Security Fix Commit FIX COMMIT
https://github.com/http4s/http4s/commit/7f065101c45f3d86bc105e8fc6323c2c4a11471f
Http4s Source Repository REPOSITORY
https://github.com/http4s/http4s
Http4s Release RELEASE
https://github.com/http4s/http4s/releases/tag/v0.23.35
Http4s Release RELEASE
https://github.com/http4s/http4s/releases/tag/v1.0.0-M47

Frequently Asked Questions

What is CVE-2026-69206?
CVE-2026-69206 is a security vulnerability in Http4s involving DigestAuth allows replay of captured requests under CWE-294: Authentication Bypass by Capture-replay.
Which Http4s versions are affected?
Affected versions include releases prior to 0.23.35, 1.0.0-M47 across affected packages: org.http4s:http4s-ember-core_2.12, org.http4s:http4s-ember-core_2.13, org.http4s:http4s-ember-core_3.
What version fixes CVE-2026-69206?
Upgrading to 0.23.35, 1.0.0-M47 (or the latest patched release for your respective branch) resolves the vulnerability.
Is http4s-ember-core_2.12 affected?
Yes, org.http4s:http4s-ember-core_2.12 is affected in releases prior to 0.23.35. Upgrade your dependency to 0.23.35 or later.
Is http4s-ember-core_2.13 affected?
Yes, org.http4s:http4s-ember-core_2.13 is affected in releases prior to 0.23.35, 1.0.0-M47. Upgrade your dependency to 0.23.35, 1.0.0-M47 or later.
What is the CVSS score of CVE-2026-69206?
CVE-2026-69206 has a CVSS v3.1 base score of 5.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-69206?
CVE-2026-69206 is classified under CWE-294: Authentication Bypass by Capture-replay (A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).).
How can I check Maven dependencies for CVE-2026-69206?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.http4s'. 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-9xww-74xv-gjfp",
  "modified" : "2026-09-15T19:54:32Z",
  "published" : "2026-09-15T19:54:32Z",
  "aliases" : [ "CVE-2026-69206" ],
  "summary" : "Http4s: DigestAuth allows replay of captured requests",
  "details" : "The `DigestAuth` replay defence stores `lastNc + 1` rather than the nonce-count (`nc`) value it just accepted. When a legitimate client sends non-contiguous `nc` values (parallel or retried requests, as browsers do), the server's counter lags behind the highest `nc` seen, and a captured `Authorization` header can be replayed multiple times.\n\n## Impact\n\nA passive observer can turn one captured Digest-authenticated request into several replayed authenticated (state-changing) requests, defeating the core\nreplay protection Digest provides over Basic.\n\n## Preconditions\n\n- Application uses `DigestAuth`.\n- Attacker can passively observe at least one legitimate digest request.\n- Legitimate client emits an `nc` more than one greater than the last, for instance from a parallel or retried request.\n\n## Workarounds\n\n- Deploy over TLS so requests cannot be captured.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.12"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.13"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.23.35"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.23.34"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_2.13"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0-M1"
      }, {
        "fixed" : "1.0.0-M47"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.0-M46"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.http4s:http4s-ember-core_3"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.0-M1"
      }, {
        "fixed" : "1.0.0-M47"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.0-M46"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/security/advisories/GHSA-9xww-74xv-gjfp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/commit/7f065101c45f3d86bc105e8fc6323c2c4a11471f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/http4s/http4s"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/releases/tag/v0.23.35"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/http4s/http4s/releases/tag/v1.0.0-M47"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-294" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-15T19:54:32Z",
    "nvd_published_at" : null
  }
}