CVE-2024-25111VulnerabilityPublished 6 Mar 2024Updated 3 Nov 2025

CVE-2024-25111: squid · Uncontrolled Recursion

Affects squidSource CVE Database V5

Not known to be exploited · 65% EPSS · CVSS 8.6 High : upgrade to 6.8 as a priority.

Data as of 26 Oct 2026, 07:57 UTC

CVSS 3.1 base score

8.6High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 65.2% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 6.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Mar 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade squid-cache/squid to 6.8.

Affected software

Product	Affected	Fixed in
GitHubsquid-cache/squid`pkg:github/squid-cache/squid`Other threats	Affected <6.8 >=3.5.27	Fixed in 6.8

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should prioritize upgrading Squid installations to version 6.8 or later, where the vulnerability is fully resolved. For environments unable to upgrade immediately, applying the official patches available in Squid's patch archives for stable releases is essential. Network administrators should implement monitoring and alerting for anomalous HTTP chunked transfer-encoded traffic patterns that may indicate exploitation attempts. Deploying rate limiting or filtering on HTTP chunked requests at perimeter devices can reduce exposure. Additionally, organizations should review proxy usage policies to limit exposure to untrusted sources and segment proxy servers to contain potential DoS impacts. Regular vulnerability scanning and asset inventory updates will help identify all affected Squid instances. Incident response plans should be updated to address potential DoS scenarios involving proxy infrastructure. Finally, maintaining up-to-date backups and redundancy for critical proxy services will aid in rapid recovery if disruption occurs.

Description

Squid is a web proxy cache. Starting in version 3.5.27 and prior to version 6.8, Squid may be vulnerable to a Denial of Service attack against HTTP Chunked decoder due to an uncontrolled recursion bug. This problem allows a remote attacker to cause Denial of Service when sending a crafted, chunked, encoded HTTP Message. This bug is fixed in Squid version 6.8. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. There is no workaround for this issue.

Impact

For European organizations, the primary impact of CVE-2024-25111 is the potential disruption of web proxy services that rely on Squid. This can lead to degraded network performance, loss of caching benefits, and interruption of HTTP traffic filtering or access controls, affecting business continuity and user productivity. Organizations using Squid as part of their security stack or content delivery infrastructure may experience outages or degraded service availability. Critical sectors such as telecommunications, financial services, government agencies, and large enterprises that depend on Squid proxies for traffic management are particularly at risk. The vulnerability does not expose sensitive data or allow code execution, but the resulting DoS can be leveraged as part of a broader attack strategy to disrupt operations. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially given the ease of exploitation and public disclosure. Failure to patch may also increase exposure to automated scanning and exploitation attempts in the near future.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 22:11 UTC

WeaknessesCWE-674

Technical details

References

Community reviews

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