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CVE-2026-61642

Squid Request Smuggling in HTTP Transfer-Encoding

No known exploitation. EPSS puts it in the 81st percentile. No fix published yet.

CVSS 3.17.7HighEPSS percentile81st2.0% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
No public exploit knownFixNone yetNo fix or workaround published
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OpenVAS · 10 checks

e.g. OID 1.3.6.1.4.1.25623.1.0.157947

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Published Updated Sources: CVE.org, NVD

NVD CVE.org

What to do

No fixed build or workaround is published yet. Limit exposure and watch for a patch.

  • Squid-cache SquidAffected: >= 3.3.0.1, < 7.6Upgrade to: not statedStated by: CVE record

Versions as the sources state them. Full version matrix after sign-in

Check it yourselfA free OpenVAS check exists for this CVE. Run it against your hosts.Is your organisation exposed?Request an assessment to establish which checks fit your systems.

What it is

From the CVE record

Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form, which the HTTP specification prohibits because any transfer coding must be wrapped within chunked encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1 is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients' future requests. This issue is fixed in version 7.6.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS81st
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

No public exploit or proof of concept found in the sources we track.

EPSS

2.0% chance of exploitation activity in the next 30 days, which ranks it in the 81st percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

5 events over 25 days, from the signal feeds we watch.

  1. Publishedweakness classified, att&ck mapped, record updated
  2. OpenVAS check added

Affected products

Technical detail

CVSS 3.1 vector

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

Scored 7.7 by NVD.

How it is reached

  • Attack Vector NetworkExploitable remotely over the network without any special conditions
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required LowRequires basic user-level privileges
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope ChangedThe exploit can affect other components (e.g. sandbox escape, host compromise from VM)

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity HighTotal loss of integrity — attacker can modify any data in the component
  • Availability NoneNo availability impact

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 3 more references. See all after sign-in

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