CVE-2026-33267Public exploitNetwork attack vector

Request smuggling via unstripped peer headers

Published Jul 29, 2026 · Updated Jul 29, 2026

Improper input validation in Apache Traffic Server 9.2.0 through 9.2.14 and 10.1.0 through 10.1.3 allows remote attackers to smuggle requests. Header sanitization leaves Connection-listed hop-by-hop headers and internal @ headers intact before plugin hooks, allowing forged metadata to influence downstream processing. Network access without authentication is sufficient; successful abuse crosses the proxy boundary to alter requests or metadata handled by plugins and upstream services.

CVSS severity7.7
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Apache Traffic Server 9.2.0 through 9.2.14 and 10.1.0 through 10.1.3 allows remote attackers to smuggle requests. Header sanitization leaves Connection-listed hop-by-hop headers and internal @ headers intact before plugin hooks, allowing forged metadata to influence downstream processing. Network access without authentication is sufficient; successful abuse crosses the proxy boundary to alter requests or metadata handled by plugins and upstream services.

The record

CVE
CVE-2026-33267
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The Apache Software Foundation
Product
Apache Traffic Server
Classifications
CWE-20, 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=10.1.0 <=10.1.3
  2. Affected versionversion=9.2.0 <=9.2.14

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Traffic Serverversion=10.1.0 <=10.1.3; version=9.2.0 <=9.2.14

Published CVSS scores

7.7Apache Software FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N
10.0Apache Software FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
9.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

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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