CVE-2026-58155Network attack vector

Policy bypass via truncated header names

Published Jul 29, 2026 · Updated Jul 29, 2026

HTTP request smuggling in Apache Traffic Server allows remote attackers to bypass proxy policy via over-long HTTP header names. Its HTTP header parser truncates a name that exceeds the supported length instead of rejecting the field, causing distinct names with matching prefixes to alias. Unauthenticated network access is sufficient to smuggle requests or make policy components interpret an attacker-supplied header as another header.

CVSS severity9.2
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Apache Traffic Server allows remote attackers to bypass proxy policy via over-long HTTP header names. Its HTTP header parser truncates a name that exceeds the supported length instead of rejecting the field, causing distinct names with matching prefixes to alias. Unauthenticated network access is sufficient to smuggle requests or make policy components interpret an attacker-supplied header as another header.

The record

CVE
CVE-2026-58155
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Apache Software Foundation
Product
Apache Traffic Server
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.0 <=10.1.3
  2. Affected versionversion=8.0.0 <=8.1.9
  3. Affected versionversion=9.0.0 <=9.2.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Traffic Serverversion=10.0.0 <=10.1.3; version=8.0.0 <=8.1.9; version=9.0.0 <=9.2.14

Published CVSS scores

9.2Apache Software FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
9.3Apache Software FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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