CVE-2023-44487

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Last Modified: UTC

Important Important Impact What does this mean?
7.5 CVSS v3 Base Score

Description

A flaw was found in handling multiplexed streams in the HTTP/2 protocol. A client can repeatedly make a request for a new multiplex stream and immediately send an RST_STREAM frame to cancel it. This creates extra work for the server setting up and tearing down the streams while not hitting any server-side limit for the maximum number of active streams per connection, resulting in a denial of service due to server resource consumption. Red Hat has rated the severity of this flaw as 'Important' as the US Cybersecurity and Infrastructure Security Agency (CISA) declared this vulnerability an active exploit.

CVE-2023-39325 was assigned for the Rapid Reset Attack in the Go language packages.

Security Bulletin This content is not included.https://access.redhat.com/security/vulnerabilities/RHSB-2023-003

Statement

NGINX has been marked as Moderate Impact because, for performance and resource consumption reasons, NGINX limits the number of concurrent streams to a default of 128. In addition, to optimally balance network and server performance, NGINX allows the client to persist HTTP connections for up to 1000 requests by default using an HTTP keepalive.

The majority of RHEL utilities are not long-running applications; instead, they are command-line tools. These tools utilize Golang package as build-time dependency, which is why they are classified as having a "Moderate" level of impact.

rhc component is no longer impacted by CVE-2023-44487 & CVE-2023-39325.

Mitigation

Users are strongly urged to update their software as soon as fixes are available.
There are several mitigation approaches for this flaw.

1. If circumstances permit, users may disable http2 endpoints to circumvent the flaw altogether until a fix is available.
2. IP-based blocking or flood protection and rate control tools may be used at network endpoints to filter incoming traffic.
3. Several package specific mitigations are also available.
     a. nginx: This content is not included.https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/
     b. netty: This content is not included.https://github.com/netty/netty/security/advisories/GHSA-xpw8-rcwv-8f8p
     c. haproxy: This content is not included.https://www.haproxy.com/blog/haproxy-is-not-affected-by-the-http-2-rapid-reset-attack-cve-2023-44487
     d. nghttp2: This content is not included.https://github.com/nghttp2/nghttp2/security/advisories/GHSA-vx74-f528-fxqg
     e. golang: The default stream concurrency limit in golang is 250 streams (requests) per HTTP/2 connection. This value may be adjusted in the golang.org/x/net/http2 package using the Server.MaxConcurrentStreams setting and the ConfigureServer function which are available in golang.org/x/net/http2.

Additional Information

External References

Content from www.cve.org is not included.https://www.cve.org/CVERecord?id=CVE-2023-44487

Content from nvd.nist.gov is not included.https://nvd.nist.gov/vuln/detail/CVE-2023-44487

Content from github.com is not included.https://github.com/dotnet/announcements/issues/277

Content from pkg.go.dev is not included.https://pkg.go.dev/vuln/GO-2023-2102

Content from www.cisa.gov is not included.https://www.cisa.gov/news-events/alerts/2023/10/10/http2-rapid-reset-vulnerability-cve-2023-44487

Content from www.nginx.com is not included.https://www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/

Content from www.cisa.gov is not included.https://www.cisa.gov/known-exploited-vulnerabilities-catalog

Affected Packages and Issued Red Hat Security Errata

Products / Services Components State Errata
.NET Core on Red Hat Enterprise Linux rh-dotnet60-dotnet Fixed RHSA-2023:5705
3scale API Management 2.13 on RHEL 7 3scale-amp2/3scale-rhel7-operator Fixed RHEA-2023:7327
A-MQ Clients 2 netty-codec-http2 Not affected
AWS-LB-OPTR-1.1-RHEL-8 albo/aws-load-balancer-rhel8-operator Fixed RHEA-2024:0555
CERT-MANAGER-1.12-RHEL-9 cert-manager/cert-manager-operator-rhel9 Fixed RHSA-2023:6269
Cost Management Metrics Operator costmanagement-metrics-operator-container Affected
Cryostat 2 netty-codec-http2 Out of support scope
Cryostat 2 on RHEL 8 cryostat-tech-preview/cryostat-grafana-dashboard-rhel8 Fixed RHSA-2023:6031
Cryostat 2 on RHEL 8 cryostat-tech-preview/cryostat-operator-bundle Fixed RHSA-2023:6031
Cryostat 2 on RHEL 8 cryostat-tech-preview/cryostat-reports-rhel8 Fixed RHSA-2023:6031
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).

CVSS v3 Score Breakdown Red Hat NVD
CVSS v3 Base Score 7.5 7.5
Attack Vector Network Network
Attack Complexity Low Low
Privileges Required None None
User Interaction None None
Scope Unchanged Unchanged
Confidentiality Impact None None
Integrity Impact None None
Availability Impact High High

CVSS v3 Vector

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

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

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

 For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

 A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

 A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

 A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

 The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

 In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our This content is not included.Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

 When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.