SB2020060327 - Amazon Linux AMI update for squid
Published: June 3, 2020
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 4 vulnerabilities.
1) Out-of-bounds write (CVE-ID: CVE-2019-12519)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a boundary error when handling the tag esi:when within ESIExpression::Evaluate. A remote attacker can pass specially crafted data to the application, trigger out-of-bounds write and execute arbitrary code on the target system.
2) Out-of-bounds write (CVE-ID: CVE-2019-12521)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a boundary error when processing untrusted input. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
3) Buffer overflow (CVE-ID: CVE-2019-12525)
CWE-ID: CWE-119 - Memory corruption
CVSSv4: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient validation of user-supplied input passed via the Proxy-Authorization header when Squid is configured to use HTTP Digest authentication . A remote attacker can send specially crafted HTTP request to the proxy server and perform denial of service attack.
4) Integer overflow (CVE-ID: CVE-2020-11945)
CWE-ID: CWE-190 - Integer overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
The vulnerability allows a remote attacker to execute arbitrary code on the target system.
The vulnerability exists due to integer overflow when processing HTTP Digest Authentication tokens, if memory pooling is disabled. A remote attacker can pass a specially crafted authentication nonce and execute arbitrary code on the server through the free'd nonce credentials.
In case memory pooling is enabled, a remote attacker can replay a sniffed Digest Authentication nonce to gain access to resources that are otherwise forbidden.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.
Remediation
Install update from vendor's website.