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CVE-2018-1172· NVD / CVE Program· CNA zdi

This vulnerability allows remote attackers to deny service on vulnerable installations of The Squid Software Foundation Squid 3.5.27-2018031

This vulnerability allows remote attackers to deny service on vulnerable installations of The Squid Software Foundation Squid 3.5.27-20180318. Authentication is not required to exploit this vulnerability. The specific flaw exists within ClientRequestContext::sslBumpAccessCheck(). A crafted request can trigger the dereference of a null pointer. An attacker can leverage this vulnerability to create a denial-of-service condition to users of the system. Was ZDI-CAN-6088.

MediumCVSS 5.9 · v3.0—No exploit Fix available
Published
May 16, 2018
Updated
Jun 16, 2026
EPSS
8.3% · 95th percentile
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Report tools

JSON

Action score

25

Monitor

Low priority for now.

CVSS
23 / 40 · 5.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 8.3%

Affected systems

VendorProduct
squid-cachesquid

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • squid-cache squid3.5.27

Versions reported by the vendor

Affected version ranges reported by the assigning authority (zdi). Independent of NVD's CPE analysis and usually ahead of it.

  • The Squid Software Foundation The Squid Software Foundation Squid

    • 3.5.27-20180318affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.10squidbefore 3.5.27-r23.5.27-r2
Debian:12squidbefore 4.1-14.1-1
openSUSE:Tumbleweedsquidbefore 4.16-1.54.16-1.5
SUSE:Linux Enterprise Server 11 SP4squid3before 3.1.23-8.16.37.6.13.1.23-8.16.37.6.1
SUSE:Linux Enterprise Server 12 SP3squidbefore 3.5.21-26.9.13.5.21-26.9.1

Same product

squid-cache: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-46847Squid: denial of service in http digest authentication
    57Plan
  • CVE-2024-25617Denial of Service in HTTP Header parser in squid proxy
    56Plan
  • CVE-2023-49285Denial of Service in HTTP Message Processing in Squid
    56Plan
  • CVE-2021-31806An issue was discovered in Squid before 4.15 and 5.x before 5.0.6.
    55Plan
  • CVE-2020-8450An issue was discovered in Squid before 4.10.
    51Plan
  • CVE-2024-25111SQUID-2024:1 Denial of Service in HTTP Chunked Decoding
    50Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:squid3.5.27-r2 · Alpine:v3.10Package registry (OSV)
debian:squid4.1-1 · Debian:12Package registry (OSV)
opensuse:squid4.16-1.5 · openSUSE:TumbleweedPackage registry (OSV)
suse:squid3.5.21-26.9.1 · SUSE:Linux Enterprise Server 12 SP3Package registry (OSV)
suse:squid33.1.23-8.16.37.6.1 · SUSE:Linux Enterprise Server 11 SP4Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

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We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records