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CVE-2018-1172

24
FAUCET Score

CVE-2018-1172 is a denial-of-service vulnerability affecting Squid versions 3.5.27 through 20180318. It allows unauthenticated remote attackers to crash the Squid proxy by sending a specially crafted request that triggers a null pointer dereference in the sslBumpAccessCheck() function. Rated Medium severity with a CVSSv3 score of 5.9, exploitation requires high attack complexity but can lead to a complete denial of service for users. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
3.5.27CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:3.5.27:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.9MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
8.61%
Probability of exploitation in next 30 days
EPSS Percentile
94.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0861 is in the 94th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (3)

redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: squid
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: squid
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: squid34

Vendor Advisories (1)

redhatCVE-2018-1172Low

squid: Incorrect pointer handling when processing ESI responses allows denial of service

Apr 18, 2018

References

zerodayinitiative.com / advisories/ZDI-18-309
Third Party AdvisoryVDB Entry
squid-cache.org / Advisories/SQUID-2018_3.txt
Vendor Advisory