CVE-2023-49286Public exploitNetwork attack vector

Service interruption via helper-startup assertion

Published Dec 4, 2023 · Updated Feb 13, 2025

Reachable assertion in Squid before 6.5 allows remote attackers to interrupt proxy service by exhausting file descriptors. The ipcCreate function passes dup failures into assertions while creating helper-process descriptors instead of handling the negative return value. A trusted client or remote server must drive the proxy under load and trigger helper startup, causing the helper process to exit.

CVSS severity8.6
High
EPSS probability10.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in Squid before 6.5 allows remote attackers to interrupt proxy service by exhausting file descriptors. The ipcCreate function passes dup failures into assertions while creating helper-process descriptors instead of handling the negative return value. A trusted client or remote server must drive the proxy under load and trigger helper startup, causing the helper process to exit.

The record

CVE
CVE-2023-49286
Published
Dec 4, 2023
Updated
Feb 13, 2025
Vendor
The Squid Software Foundation
Product
Squid
Classifications
CWE-253, CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 6.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Squid Software Foundation · Squidversion=< 6.5

Published CVSS scores

8.6GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-253Incorrect Check of Function Return Value
CWE-617Reachable Assertion
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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