CVE-2026-61642: Squid3 · Squid is a caching proxy for the Web
Affects squid3Source GCVE Database
Not known to be exploited · CVSS 7.7 High · fixed in 3.5.12-1ubuntu7.16+esm7 : patch squid3 soon.
Data as of 2 Nov 2026, 22:58 UTC
- EPSS
- 2.0% chance of exploitation in 30 days – higher than 81% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.5.12-1ubuntu7.16+esm7, 3.5.27-1ubuntu1.14+esm6, 4.10-1ubuntu1.13+esm3 +2
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 13 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSsquidpkg:deb/ubuntu/squid?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSsquidpkg:deb/ubuntu/squid?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSsquidpkg:deb/ubuntu/squid?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu Pro 20.04 LTSsquidpkg:deb/ubuntu/squid?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in
|
Ubuntu Pro 18.04 LTSsquid3pkg:deb/ubuntu/squid3?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in
|
Ubuntu Pro 16.04 LTSsquid3pkg:deb/ubuntu/squid3?arch=source&distro=esm-infra-legacy/xenialOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available and has been released in Squid version 7.6. Ubuntu has provided updated package versions for all affected LTS releases, including 16.04, 18.04, 20.04, 22.04, and 24.04. Users should update their Squid installations to the patched versions as provided by their distribution to remediate this vulnerability. Standard system updates on Ubuntu will apply these fixes. No additional mitigation steps are required beyond applying the official patches.
Description
Squid versions from 3.3.0.1 up to but not including 7.6 contain a vulnerability in HTTP/1.1 Transfer-Encoding header parsing that allows a trusted client to perform HTTP Request Smuggling attacks. This flaw arises from improper enforcement of HTTP specifications regarding the Transfer-Encoding header, enabling attackers to bypass security mechanisms and potentially poison upstream web caches. The issue is fixed in Squid version 7.6. Ubuntu has released patches for multiple affected versions across various LTS releases.