Debian Security Advisory
DLA-2394-1 squid3 -- LTS security update
- Date Reported:
- 02 Oct 2020
- Affected Packages:
- Security database references:
- In Mitre's CVE dictionary: CVE-2020-15049, CVE-2020-15810, CVE-2020-15811, CVE-2020-24606.
- More information:
Several security vulnerabilities have been discovered in Squid, a highperformance proxy caching server for web clients.
An issue was discovered in http/ContentLengthInterpreter.cc in Squid. A Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP request with a Content Length header containing "+\ "-" or an uncommon shell whitespace character prefix to the length field-value. This update also includes several other improvements to the HttpHeader parsing code.
Due to incorrect data validation, HTTP Request Smuggling attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning and allows any client, including browser scripts, to bypass local security and poison the proxy cache and any downstream caches with content from an arbitrary source. When configured for relaxed header parsing (the default), Squid relays headers containing whitespace characters to upstream servers. When this occurs as a prefix to a Content-Length header, the frame length specified will be ignored by Squid (allowing for a conflicting length to be used from another Content-Length header) but relayed upstream.
Squid allows a trusted peer to perform Denial of Service by consuming all available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply() livelocking in peer_digest.cc mishandles EOF.
For Debian 9 stretch, these problems have been fixed in version 3.5.23-5+deb9u5.
We recommend that you upgrade your squid3 packages.
For the detailed security status of squid3 please refer to its security tracker page at: https://security-tracker.debian.org/tracker/squid3
Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: https://wiki.debian.org/LTS