VulnerabilityPublished 10 Oct 2023Updated 4 Nov 2025

CVE-2023-44487: August · Uncontrolled Resource Consumption

Source CVE Database V5

Exploited in the wild · KEV due 31 Oct 2023 · public exploit available (Exploit-DB) · 99% EPSS : apply the vendor's fix or mitigations to affected systems now.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

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

KEV deadline: 31 Oct 2023 US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
EPSS: 99.9% chance of exploitation in 30 days – higher than 99% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

t = 0 is the CVE’s publication on cve.org

Disclosed: evidence found.
CVE published 10 Oct 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
1 Exploit-DB entry, 1.9 years after disclosure
Exploited in the wildExploited: evidence found.
Listed in CISA KEV the same day as disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

CVE ID reserved
by MITRE Corporation
29 Sep 2023, 11 days before disclosure
CVE published
on cve.org
10 Oct 2023, t = 0
Added to CISA KEV (opens in a new tab)
exploitation confirmed
10 Oct 2023, the same day as disclosure
KEV remediation due
US federal deadline
31 Oct 2023, 21 days after disclosure
First Exploit-DB entry (opens in a new tab)
HTTP/2 2.0 - Denial Of Service (DOS)
16 Sep 2025, 1.9 years after disclosure

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Description

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

Impact

For European organizations, the primary impact is service disruption due to denial of service attacks targeting HTTP/2-enabled web servers or proxies. This can lead to downtime of critical web applications, loss of availability for customers and internal users, and potential reputational damage. Organizations providing online services, e-commerce platforms, financial institutions, and public sector entities are particularly vulnerable as they often rely heavily on HTTP/2 for performance improvements. The attack can degrade server performance, increase operational costs due to resource exhaustion, and potentially cascade into broader network disruptions if mitigation is not promptly applied. Given the remote and unauthenticated nature of the exploit, attackers can launch large-scale attacks with minimal effort, increasing the risk of widespread outages. The lack of specific vendor patches at the time of reporting means organizations must proactively implement mitigations to reduce exposure. The impact is amplified in countries with dense internet infrastructure and high volumes of HTTP/2 traffic, where attackers may seek to disrupt critical digital services.

Mitigation

1. Implement rate limiting on HTTP/2 stream resets and cancellations to prevent rapid, repeated resets from overwhelming server resources. 2. Configure web servers and proxies to detect and block suspicious patterns of request cancellations indicative of attack behavior. 3. Monitor HTTP/2 traffic for abnormal spikes in stream resets and cancellations to enable early detection of exploitation attempts. 4. Apply any vendor patches or updates as soon as they become available, prioritizing HTTP/2 stack components in web servers, load balancers, and proxies. 5. Consider temporarily disabling HTTP/2 support on critical servers if mitigation options are limited and the risk of attack is high. 6. Harden server resource allocation and implement connection throttling to reduce the impact of resource exhaustion attacks. 7. Employ Web Application Firewalls (WAFs) or Intrusion Prevention Systems (IPS) with signatures or heuristics targeting this specific attack pattern. 8. Conduct regular security assessments and stress testing to evaluate server resilience against HTTP/2-based DoS attacks. These steps go beyond generic advice by focusing on HTTP/2-specific behaviors and proactive monitoring tailored to this vulnerability.

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

Community reviews

Loading reviews…

Exploitation evidence

Timeline

What to do

Description

AI analysisMachine-generated, updated 4 Nov 2025, 21:37 UTC

Public exploits and detection1 Exploit-DB entry

WeaknessesCWE-400

Technical details

References

Community reviews

Related threats