CVE-2019-12521

MEDIUM
5.9
CVSS Score
Published: April 15, 2020 at 06:47 PM UTC
Updated: June 17, 2026 at 02:14 AM UTC
4 products affected across 4 vendorsDebian LinuxUbuntu LinuxLeap

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Severity
MEDIUM5.9
Exploit prediction
EPSS 6%

Description

An issue was discovered in Squid through 4.7. 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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.0 ≤ v ≤ 3.5.284.0 ≤ v ≤ 4.75.0 ≤ v ≤ 5.0.1

References (8)

Vendor Advisoryx_refsource_SUSEMailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00018.html
Mailing Listx_refsource_MLISTPatchThird Party Advisory
http://www.openwall.com/lists/oss-security/2020/04/23/1
Mailing Listx_refsource_MLISTThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.html
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
https://security.gentoo.org/glsa/202005-05
Vendor Advisoryx_refsource_UBUNTUThird Party Advisory
https://usn.ubuntu.com/4356-1/
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
https://www.debian.org/security/2020/dsa-4682

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-193CWE-787

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