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Fencer Vulns
high 7.7

CVE-2026-61642 json

Squid Request Smuggling in HTTP Transfer-Encoding

published 2026-10-13 26 d ago modified 2026-10-16 23 d ago also EUVD-2026-98919

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

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.

Patch / fix

  • squid-cache squid 7.6
  • squid Debian 13 6.13-2+deb13u4
  • squid Debian 14 7.6-1

debian advisories DEBIAN-CVE-2026-61642

  • squid Ubuntu 22.04 LTS 5.9-0ubuntu0.22.04.8
  • squid Ubuntu 24.04 LTS 6.14-0ubuntu0.24.04.5
  • squid Ubuntu 26.04 LTS 7.7-0ubuntu0.26.04.2
  • squid Ubuntu Pro 20.04 LTS 4.10-1ubuntu1.13+esm3
  • squid3 Ubuntu Pro 16.04 LTS 3.5.12-1ubuntu7.16+esm7
  • squid3 Ubuntu Pro 18.04 LTS 3.5.27-1ubuntu1.14+esm6

ubuntu advisories UBUNTU-CVE-2026-61642

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1985+eaf982f0.6
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+2080+49064dbd.9
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+40156+3f7c6af1.11
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+40253+79b268c3.12
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1758+80ba9f4b
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1881+7e31fb44.1
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1885+e30b7122.3
  • squid Rocky Linux 8 7:4.15-10.module+el8.10.0+1928+e8441768.5

rocky linux advisories RLSA-2026:96078

  • squid Azure Linux 3.0 6.13-6

azure linux advisories AZL-108531

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-61642 updated cvss 7.7

squid: squid: Request Smuggling in HTTP Transfer-Encoding

  • Red Hat Enterprise Linux 6 squid, squid34, squid 6.10-15.el10 Red Hat Enterprise Linux 7 squid, squid-sysvinit, squid 6.10-15.el10, squid-migration-script Red Hat Enterprise Linux 9 squid, squid 6.10-15.el10 Red Hat Enterprise Linux 10 squid 6.10-15.el10
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) libecap 1.0.1-2.module+el8.9.0+19703+a1da7223, squid 4.15-10.module+el8.10.0+25179+3c013c36.13
    fixed: vendor fix RHSA-2026:96078

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
26 d ago

Exploit prediction

2.04% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

Affected products

  • squid-cache squid

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.