Is CVE-2019-12521 actively exploited?

CVE-2019-12521 has no public evidence of in-the-wild exploitation as of 2024-11-21.

What is the CVSS score for CVE-2019-12521?

CVE-2019-12521 has a CVSS score of 5.9 (MEDIUM severity). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

How do I patch CVE-2019-12521?

Patch guidance is available from squid-cache security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2019-12521.

CVE-2019-12521 - remediation guidance & executive summary

Q: Which products are affected by CVE-2019-12521?

10 products: squid-cache squid, squid-cache squid, squid-cache squid, canonical ubuntu linux, canonical ubuntu linux, and 5 more.

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.

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: high
Weaknesses: CWE-193 CWE-787 · Out-of-bounds Write

Metadata

Primary Vendor: SQUID-CACHE
Published: 4/15/2020
Last Modified: 11/21/2024
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

squid-cache : squidsquid-cache : squidsquid-cache : squidcanonical : ubuntu_linuxcanonical : ubuntu_linuxcanonical : ubuntu_linuxcanonical : ubuntu_linuxdebian : debian_linuxdebian : debian_linuxopensuse : leap

Remediation Guidance

Executive Summary

Cite this page

CVE-2019-12521. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2019-12521

View on NIST NVD

CVE-2019-12521 vulnerability