Home/CVE/An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESICon
CVE

CVE-2019-12521

An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in ESIContext. ESICon

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.

MEDIUM · CVSS 5.9 EPSS 0.00565
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-193Off-by-one Error
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

6
squid-cache squid>= 3.0 and <= 3.5.28
squid-cache squid>= 4.0 and <= 4.7
squid-cache squid>= 5.0 and <= 5.0.1
canonical ubuntu linuxall versions
debian linuxall versions
opensuse leapall versions
▣

Scoring & Timeline

5.9
MEDIUM · CVSS v3.1 · cve@mitre.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD15 Apr 2020 · 07:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
⚑

Vendor Advisories

7
suse-csafSUSE-SU-2020:14460-1
rhsaRHSA-2020:4743Moderate
usnUSN-4356-1
suse-csafopenSUSE-SU-2020:0623-1
suse-csafSUSE-SU-2020:1227-1
🔗

References & Sources

8
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00018.htmlMailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2020/04/23/1Mailing ListPatchThird Party Advisory
https://gitlab.com/jeriko.one/security/-/blob/master/squid/CVEs/CVE-2019-12521.txtThird Party Advisory
https://lists.debian.org/debian-lts-announce/2020/07/msg00009.htmlMailing ListThird Party Advisory
https://security.gentoo.org/glsa/202005-05Third Party Advisory
https://security.netapp.com/advisory/ntap-20210205-0006/Third Party Advisory
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