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Traffic ServerApplication · Apache

CVE-2026-58155

CRITICAL · 9.3 CVSS v3.1 Published 2026-07-29
Fix available
A fix is available. Upgrade to 9.2.15 / 10.1.4 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 3 weeks old

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
Apache Traffic Server truncates over-long header names, allowing header aliasing, request smuggling, and policy bypass. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.

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 improperly truncates HTTP header names that exceed a certain length, causing different headers to become aliased to the same name. This allows attackers to smuggle requests through the proxy, bypass security policies, and potentially manipulate traffic routing.

MitigationUpgrade Apache Traffic Server to version 9.2.15 or 10.1.4 to resolve the header truncation vulnerability.

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, <= 8.1.9>= 9.0.0, < 9.2.15>= 10.0.0, < 10.1.4

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
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
None

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

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 installed Apache Traffic Server version
    Run 'traffic_server -V' or 'traffic_ctl config get version' from the command line to obtain the exact version number
    Affected if Version falls within 8.0.0-8.1.9, 9.0.0-9.2.14, or 10.0.0-10.1.3
  2. Confirm Traffic Server is processing HTTP traffic
    Check if traffic_server process is running and inspect records.config for proxy.config.http.enabled or similar HTTP proxy settings
    Affected if Traffic Server is active as an HTTP proxy or reverse proxy handling incoming requests
  3. Test for header name truncation
    Send HTTP requests with header names exceeding typical length limits (e.g., >64 characters) and verify if distinct headers are incorrectly treated as duplicates or aliases
    Affected if Long header names are being collapsed or treated as the same header, indicating truncation is occurring

The environment is affected if the installed Apache Traffic Server version is 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, or 10.0.0 through 10.1.3 and the server processes HTTP traffic with long header names.

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 9.2.15 / 10.1.4 or later
Fixed in 9.2.1510.1.4
Interim mitigation

Upgrade Apache Traffic Server to version 9.2.15 or 10.1.4 to resolve the header truncation vulnerability.

Recommended fix High confidence

Apache Traffic Server 10.1.4 (or 9.2.15 for LTS track)

  1. 1. Identify the currently installed Apache Traffic Server version using 'traffic_server -V' or checking package management
  2. 2. Back up the entire Apache Traffic Server configuration directory (typically /etc/trafficserver or /usr/local/etc/trafficserver)
  3. 3. Back up any custom plugins or scripts used with Traffic Server
  4. 4. Stop the Apache Traffic Server service using 'trafficctl server stop' or the system service manager (e.g., 'systemctl stop trafficserver')
  5. 5. Install the fixed version: upgrade to Apache Traffic Server 9.2.15 or 10.1.4 using your package manager or compile from source
  6. 6. Verify the new version is installed by running 'traffic_server -V'
  7. 7. Restore any custom configuration files from the backup if needed
  8. 8. Start the Apache Traffic Server service using 'trafficctl server start' or the system service manager
Caveat Minor version upgrades typically retain configuration compatibility, but test in staging before production deployment

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

Fix this in Traffic Server Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2026-58155 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