Medium [CVE-2026-47729] memory disclosure in FTP gateway
This medium-severity Red Hat Linux advisory covers CVE-2026-47729 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
Squid is a caching proxy for the Web.
Prior to 7.6, due to an improper validation of syntactic correctness of input in the FTP gateway (src/clients/FtpGateway.cc), Squid is vulnerable to an out-of-bounds read: when a listing entry date in the TypeA or TypeB directory-listing formats is not followed by a filename, parsing was not restricted to the input buffer, so a trusted client accessing a misbehaving FTP server through Squid's gateway feature could read memory from random unrelated transactions.
This issue is fixed in version 7.6. To exploit this issue, an attacker must have a valid account on the Squid proxy and must also control an FTP server reachable from the proxy on port 21.
The impact is limited to information disclosure of cleartext HTTP request contents or traffic in TLS-terminating (SSL bump) proxy configurations where Squid decrypts and inspects traffic. FTP protocol usage has declined considerably in most environments since major browsers removed FTP support, further narrowing the practical attack surface.
Due to these reasons, this vulnerability has been rated with a moderate severity. Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N).
Weakness: CWE-125. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
- < 7.6
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
Mitigation checklist
- When FTP access is not required, block FTP traffic at the proxy by adding the following settings to the squid.conf configuration file above any custom 'http_access allow' rules: ~~~ acl FTP proto FTP http_access deny FTP ~~~ When FTP access is required, configure Squid to only allow FTP access to specific and trusted destination domains. See the example below for restricting FTP access to the 'trusted.server.example.com' domain: ~~~ acl FTP proto FTP acl ftp_allowlist dstdomain .trusted.server.example.com http_access deny FTP !ftp_allowlist ~~~
Official advisory · high-confidence parse· fetched 15 days ago·verify at source
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