An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode. uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The length is then used to start decoding the string. There are no checks to ensure that the length it calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the display of usernames on error pages.
http://www.squid-cache.org/Versions/v4/changesets/
https://github.com/squid-cache/squid/commits/v4
https://usn.ubuntu.com/4065-1/
https://lists.debian.org/debian-lts-announce/2019/07/msg00018.html
https://usn.ubuntu.com/4065-2/
https://www.debian.org/security/2019/dsa-4507
https://seclists.org/bugtraq/2019/Aug/42
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00056.html
http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00053.html
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html
Source: MITRE
Published: 2019-07-11
Updated: 2022-04-26
Type: CWE-125
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.9
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 2.2
Severity: MEDIUM