CVE-2019-12529
squid: Out of bounds read in Proxy-Authorization header causes DoS
Severity
ModerateRed Hat Product Security
CVSS 3.0
Review impact separately from score.
Published · July 11, 2019
Updated · November 22, 2025
Description
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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Remove 'auth_param basic ...' configuration settings from squid.conf
CVSS / CWE
CVSS 3.0 · 4.3CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer