VulnerabilityPublished 21 Apr 2026

CVE-2026-41135: free5gc pcf · Uncontrolled Resource Consumption

Affects free5gc pcfSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 1.4.3 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.4.3

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
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: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
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 21 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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 pcf and free5gc/pcf to 1.4.3.

Affected software

Product	Affected	Fixed in
free5gcpcf	Affected <1.4.3	Fixed in 1.4.3
GitHubfree5gc/pcf`pkg:github/free5gc/pcf`Other threats	Affected <1.4.3	Fixed in 1.4.3

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

AI-suggested

A patch is available in free5GC version 1.4.3 that fixes the memory leak vulnerability. Users should upgrade to version 1.4.3 or later to remediate this issue. Since this is not a cloud service, remediation depends on applying the official fix. Patch status beyond the version update is not explicitly stated, so check the vendor advisory for the latest guidance.

Description

CVE-2026-41135 is a memory leak vulnerability in free5GC's Policy Control Function (PCF) affecting versions prior to 1.4.3. An unauthenticated attacker with network access to the PCF SBI interface can cause uncontrolled memory growth by repeatedly sending HTTP requests to the OAM endpoint. This occurs because a new CORS middleware is registered on every incoming request, causing the Gin router's handler chain to grow indefinitely. The resulting memory exhaustion leads to denial of service, preventing user equipment from obtaining necessary policies and blocking 5G session establishment. Version 1.4.3 includes a patch to fix this issue.

Impact

An unauthenticated attacker can exploit this vulnerability remotely to cause uncontrolled memory consumption on the PCF, leading to denial of service. This disrupts the delivery of access and session management policies to user equipment, effectively blocking 5G session establishment. The impact is high availability degradation of the 5G core network's policy control function, potentially affecting network operations and user connectivity.

Summary

The vulnerability in free5GC PCF (CVE-2026-41135) is due to a memory leak caused by improper middleware registration within an HTTP handler. Specifically, the router.Use() call inside the handler registers a new CORS middleware on every request, causing the Gin router's handler chain to grow without bounds. This leads to progressive memory exhaustion and ultimately denial of service of the PCF component. The PCF is critical for policy control in 5G core networks, and its failure disrupts policy delivery and session establishment for user equipment. The issue affects all versions before 1.4.3, which contains a patch addressing this problem.

CWE-400Uncontrolled Resource Consumption (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product does not properly control the allocation and maintenance of a limited resource.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place.
Architecture and Design
Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or; uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed.
Architecture and Design
Ensure that protocols have specific limits of scale placed on them.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Regular Expression Exponential Blowup (opens in a new tab)
Sustained Client Engagement (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 29 Apr 2026, 11:29 UTC

WeaknessesCWE-400

Technical details

References

Community reviews

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