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Traffic ServerApplication · Apache

CVE-2021-44759

HIGH · 8.1 CVSS v3.1 Published 2022-03-23
Fix available
A fix is available. Upgrade to after 8.1.0 or later.
See remediation →
90/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper Authentication vulnerability in TLS origin validation of Apache Traffic Server allows an attacker to create a man in the middle attack. This issue affects Apache Traffic Server 8.0.0 to 8.1.0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Apache Traffic Server 8.0.0 to 8.1.0 contains an improper authentication vulnerability in TLS origin validation. The server fails to properly validate TLS certificates or connections to origin servers, allowing an attacker positioned on the network path to intercept or modify traffic between the ATS proxy and origin servers (MITM attack).

MitigationUpgrade Apache Traffic Server to version 8.1.1 or later. If immediate upgrade is not possible, implement additional network-level controls to protect the path between ATS and origin servers.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Traffic ServerApplication
Affected:>= 8.0.0, <= 8.1.0
Debian LinuxOperating system
Affected:= 10.0= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Determine Apache Traffic Server version
    Run 'traffic_server -V' or check package manager (dpkg -l traffic-server, rpm -q traffic-server)
    Affected if Installed version is 8.0.0 through 8.1.0 (inclusive)
  2. Verify TLS origin connections are configured
    Examine remap.config or records.conf for 'proxy.config.http.origin_server' settings; check if any remap rules point to https:// origins
    Affected if ATS is configured to forward traffic to origin servers over HTTPS
  3. Inspect TLS certificate validation settings
    Check records.conf for 'proxy.config.ssl.origin.verify' and 'proxy.config.ssl.origin.verify_ca' settings; look for values that disable certificate validation
    Affected if TLS verification is disabled or set to allow untrusted certificates for origin connections
  4. Review SSL origin server configuration
    Examine ssl_multicert.config and verify 'dest' or 'client_cert' settings for origin-facing TLS; check if any configurations bypass normal TLS validation
    Affected if Origin TLS is configured in a way that bypasses standard certificate validation

A system is affected if Apache Traffic Server version 8.0.0-8.1.0 is in use AND the server is configured to proxy client requests to HTTPS origin servers, allowing potential MITM interception of origin traffic.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 8.1.0
Interim mitigation

Upgrade Apache Traffic Server to version 8.1.1 or later. If immediate upgrade is not possible, implement additional network-level controls to protect the path between ATS and origin servers.

Recommended fix Moderate confidence

Apache Traffic Server 8.1.1 or later / latest stable 9.x release

  1. 1. Identify the current Apache Traffic Server version installed (e.g., `traffic server version` or check package manager)
  2. 2. Upgrade to Apache Traffic Server version 8.1.1 or later (or the latest stable 9.x release if available and compatible)
  3. 3. Verify the upgrade by checking the new version: `traffic server version`
  4. 4. Test TLS origin validation functionality to confirm the fix works correctly
  5. 5. For Debian systems, apply security updates via: `apt update && apt upgrade` or install the specific fixed packages from Debian security advisories (DSA or DLA)
Caveat Review release notes for any configuration or behavior changes between 8.0.x/8.1.x and the target version; test in non-production first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Traffic Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,100
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,960.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-44759 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data