CVE-2026-61642Network attack vectorHinoki check available

Security bypass via accepted identity transfer encoding

Published Oct 13, 2026 · Updated Oct 13, 2026

Request smuggling in Squid 3.3.0.1 through 7.5 allows attackers to bypass intermediary security via HTTP/1.1 headers. HttpHeader::parse in src/HttpHeader.cc accepts bare Transfer-Encoding identity and deletes that header instead of rejecting a coding without chunked framing. Exploitation requires a trusted client; a cache ahead of Squid also enables poisoning with arbitrary malicious content served to later clients.

CVSS severity7.7
High
EPSS probability4.68%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Request smuggling in Squid 3.3.0.1 through 7.5 allows attackers to bypass intermediary security via HTTP/1.1 headers. HttpHeader::parse in src/HttpHeader.cc accepts bare Transfer-Encoding identity and deletes that header instead of rejecting a coding without chunked framing. Exploitation requires a trusted client; a cache ahead of Squid also enables poisoning with arbitrary malicious content served to later clients.

The record

CVE
CVE-2026-61642
Published
Oct 13, 2026
Updated
Oct 13, 2026
Vendor
The Squid Software Foundation
Product
Squid
Classifications
CWE-444, CWE-841, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Oct 13, 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=>= 3.3.0.1, < 7.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Squid Software Foundation · Squidversion=>= 3.3.0.1, < 7.6

Published CVSS scores

7.7Squid upstreamCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
7.7Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CWE-841Improper Enforcement of Behavioral Workflow
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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