CVE-2025-53633VulnerabilityPublished 10 Jul 2025

CVE-2025-53633: ctfer-io chall-manager · Asymmetric Resource Consumption (Amplification)

Affects ctfer-io chall-managerSource CVE Database V5

Not known to be exploited · CVSS 8.7 High : upgrade to 0.1.4 soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score

8.7High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.1.4

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: High
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

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

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, 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: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: High: There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; 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 Vulnerable System (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).
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Jul 2025
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 ctfer-io/chall-manager to 0.1.4.

Affected software

Product	Affected	Fixed in
GitHubctfer-io/chall-manager`pkg:github/ctfer-io/chall-manager`Other threats	Affected <0.1.4	Fixed in 0.1.4

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

AI-suggested

1. Immediate upgrade to ctfer-io chall-manager version 0.1.4 or later, which includes the patch to validate decompressed content size and prevent zip bomb exploitation. 2. Network segmentation: Ensure chall-manager instances are deployed within isolated, internal network zones inaccessible from the public internet or untrusted networks. 3. Implement strict ingress filtering and firewall rules to restrict access to the chall-manager service only to trusted IP addresses or VPNs. 4. Monitor resource usage closely on servers running chall-manager for unusual spikes in CPU, memory, or disk utilization that may indicate exploitation attempts. 5. Employ application-layer controls such as file upload size limits and scanning of uploaded archives for malicious content before processing. 6. Conduct regular security audits and penetration tests focusing on chall-manager deployment to verify proper isolation and patch status. 7. Maintain up-to-date incident response plans to quickly identify and mitigate DoS attacks stemming from this vulnerability.

Description

Chall-Manager is a platform-agnostic system able to start Challenges on Demand of a player. When decoding a scenario (i.e.a zip archive), the size of the decoded content is not checked, potentially leading to zip bombs decompression. Exploitation does not require authentication nor authorization, so anyone can exploit it. It should nonetheless not be exploitable as it is highly recommended to bury Chall-Manager deep within the infrastructure due to its large capabilities, so no users could reach the system. Patch has been implemented by commit 14042aa and shipped in v0.1.4.

Impact

For European organizations using ctfer-io chall-manager, this vulnerability poses a significant risk to system availability and operational continuity. An attacker could remotely deploy a zip bomb to exhaust server resources, leading to service outages or degraded performance. This is particularly critical in environments where chall-manager is integrated into competitive or training platforms, such as cybersecurity competitions, educational institutions, or research labs. The lack of authentication requirements increases the attack surface, potentially allowing external threat actors to disrupt services without insider access. Additionally, if chall-manager is part of a larger infrastructure handling sensitive or time-critical challenges, the DoS could cascade, affecting dependent systems and users. European organizations with strict uptime requirements or regulatory obligations around service availability (e.g., financial institutions, critical infrastructure operators) may face compliance risks or reputational damage if impacted. Although the vendor recommends isolating chall-manager within secure network segments, misconfigurations or exposure to public networks could increase exploitation likelihood.

CWE-405Asymmetric Resource Consumption (Amplification) (opens in a new tab)
Class weakness
The product does not properly control situations in which an adversary can cause the product to consume or produce excessive resources without requiring the adversary to invest equivalent work or otherwise prove authorization, i.e., the adversary's influence is "asymmetric."
Architecture and Design
An application must make resources available to a client commensurate with the client's access level.
Architecture and Design
An application must, at all times, keep track of allocated resources and meter their usage appropriately.
System Configuration
Consider disabling resource-intensive algorithms on the server side, such as Diffie-Hellman key exchange.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jul 2025, 20:01 UTC

WeaknessesCWE-405

Technical details

References

Community reviews

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