Request smuggling due to improper request handling in golang.org/x/net/http2/h2c
golang.org/x/net · golang.org/x/net/http2/h2c
7.5HighCVSS 3.1
Recommended action
Within 7 days
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 4 Apr 2025
Evidence used
No CISA KEV confirmation is currently recorded.
A structured source references public exploit or proof-of-concept material.
The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
EPSS is 1.81% for the current model date.
Compensating controls
Validate the affected product branch and deploy the verified fixed release.
Restrict the affected network interface to trusted sources where business-safe.
Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
Confirm that the asset runs golang.org/x/net golang.org/x/net/http2/h2c and falls inside the recorded affected range.
Verify the installed build against the product-specific fixed version after deployment.
Validate exposure, authentication requirements and compensating controls in the actual environment.
Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
Release-specific package status
Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
4 package states
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
Distribution release
Source package
Vendor state
Fixed version
Evidence
Debian trixietrixie · source
golang-golang-x-net
Vendor fix publishedDebian records a fixed source-package version for this release.
Open-source package ranges1 source-attributed range
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
The vendor explicitly identifies these products as affected by this CVE.
cli as a component of OpenShift Serverless
knative-eventing as a component of OpenShift Serverless
knative-serving as a component of OpenShift Serverless
servicemesh as a component of OpenShift Service Mesh 2.1
servicemesh-cni as a component of OpenShift Service Mesh 2.1
servicemesh-pilot-agent as a component of OpenShift Service Mesh 2.1
servicemesh-pilot-discovery as a component of OpenShift Service Mesh 2.1
servicemesh.src as a component of OpenShift Service Mesh 2.1
openshift-service-mesh/istio-cni-rhel8 as a component of OpenShift Service Mesh 2
rhacm2/kube-rbac-proxy-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2
rhacm2/thanos-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2
advanced-cluster-security/rhacs-main-rhel8 as a component of Red Hat Advanced Cluster Security 3
Summary
A request smuggling attack is possible when using MaxBytesHandler. When using MaxBytesHandler, the body of an HTTP request is not fully consumed. When the server attempts to read HTTP2 frames from the connection, it will instead read the body of the HTTP request, which could be attacker-manipulated to represent arbitrary HTTP2 requests.
Remediation
For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.13/release_notes/ocp-4-13-release-notes.html You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags The sha values for the release are: (For x86_64 architecture) The image digest is sha256:74b23ed4bbb593195a721373ed6693687a9b444c97065ce8ac653ba464375711 (For s390x architecture) The image digest is sha256:a32d509d960eb3e889a22c4673729f95170489789c85308794287e6e9248fb79 (For ppc64le architecture) The image digest is sha256:bca0e4a4ed28b799e860e302c4f6bb7e11598f7c136c56938db0bf9593fb76f8 (For aarch64 architecture) The image digest is sha256:e07e4075c07fca21a1aed9d7f9c165696b1d0fa4940a219a000894e5683d846c All OpenShift Container Platform 4.13 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift Console or the CLI oc command. Instructions for upgrading a cluster are available at https://docs.openshift.com/container-platform/4.13/updating/updating-cluster-cli.html
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2023-0462
No EUVD known-exploited evidence
ENISA has published the identifier mapping but no EUVD description has been stored yet.
EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available
01
What, why and how
A request smuggling attack is possible when using MaxBytesHandler. When using MaxBytesHandler, the body of an HTTP request is not fully consumed. When the server attempts to read HTTP2 frames from the connection, it will instead be reading the body of the HTTP request, which could be attacker-manipulated to represent arbitrary HTTP2 requests.
What
A request smuggling attack is possible when using MaxBytesHandler. When using MaxBytesHandler, the body of an HTTP request is not fully consumed. When the server attempts to read HTTP2 frames from the connection, it will instead be reading the body of the HTTP request, which could be attacker-manipulated to represent arbitrary HTTP2 requests.
Why
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
A request smuggling attack is possible when using MaxBytesHandler. When using MaxBytesHandler, the body of an HTTP request is not fully consumed. When the server attempts to read HTTP2 frames from the connection, it will instead be reading the body of the HTTP request, which could be attacker-manipulated to represent arbitrary HTTP2 requests.
Why
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No confirmed evidence
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.Reference recorded
A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
Likely attack path
a network path → Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'). The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
Ein Angreifer kann mehrere Schwachstellen in Dell ECS ausnutzen, um seine Privilegien zu erweitern, beliebigen Programmcode mit Administratorrechten auszuführen, Informationen offenzulegen, Dateien zu manipulieren, einen Cross-Site-Scripting-Angriff durchzuführen, Sicherheitsvorkehrungen zu umgehen oder einen Denial of Service Zustand herbeizuführen.
Official advisory ↗Cyber Security Agency of Singapore · English · CSA-SB-20230118Security Bulletin 18 Jan 2023
The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 18 Jan 2023, published on 18 January 2023. Open the linked bulletin for the product, severity and reference information published in that issue.
Official advisory ↗CERT-FR · French · CERTFR-2026-AVI-0109Multiples vulnérabilités dans les produits IBM
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.13/release_notes/ocp-4-13-release-notes.html You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags The sha values for the release are: (For x86_64 architecture) The image digest is sha256:74b23ed4bbb593195a721373ed6693687a9b444c97065ce8ac653ba464375711 (For s390x architecture) The image digest is sha256:a32d509d960eb3e889a22c4673729f95170489789c85308794287e6e9248fb79 (For ppc64le architecture) The image digest is sha256:bca0e4a4ed28b799e860e302c4f6bb7e11598f7c136c56938db0bf9593fb76f8 (For aarch64 architecture) The image digest is sha256:e07e4075c07fca21a1aed9d7f9c165696b1d0fa4940a219a000894e5683d846c All OpenShift Container Platform 4.13 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift Console or the CLI oc command. Instructions for upgrading a cluster are available at https://docs.openshift.com/container-platform/4.13/updating/updating-cluster-cli.html
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 13 Jan 2023 · Last source change 4 Apr 2025, 14:46 UTC · CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2023-0462
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceNIST NVD
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Affected versionsThe structured affected or fixed version information changed.
Before
0.0.0-20220524220425-1d687d428aca < 0.1.1-0.20221104162952-702349b0e862 · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
After
0.0.0-20220524220425-1d687d428aca < 0.1.1-0.20221104162952-702349b0e862 · Fixed: For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.openshift.com/container-platform/4.13/release_notes/ocp-4-13-release-notes.html You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags The sha values for the release are: (For x86_64 architecture) The image digest is sha256:74b23ed4bbb593195a721373ed6693687a9b444c97065ce8ac653ba464375711 (For s390x architecture) The image digest is sha256:a32d509d960eb3e889a22c4673729f95170489789c85308794287e6e9248fb79 (For ppc64le architecture) The image digest is sha256:bca0e4a4ed28b799e860e302c4f6bb7e11598f7c136c56938db0bf9593fb76f8 (For aarch64 architecture) The image digest is sha256:e07e4075c07fca21a1aed9d7f9c165696b1d0fa4940a219a000894e5683d846c All OpenShift Container Platform 4.13 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift Console or the CLI oc command. Instructions for upgrading a cluster are available at https://docs.openshift.com/container-platform/4.13/updating/updating-cluster-cli.html
Affected versionsThe structured affected or fixed version information changed.
Before
cli as a component of OpenShift Serverless; knative-eventing as a component of OpenShift Serverless; knative-serving as a component of OpenShift Serverless; servicemesh as a component of OpenShift Service Mesh 2.1; servicemesh-cni as a component of OpenShift Service Mesh 2.1; servicemesh-pilot-agent as a component of OpenShift Service Mesh 2.1; servicemesh-pilot-discovery as a component of OpenShift Service Mesh 2.1; servicemesh.src as a component of OpenShift Service Mesh 2.1; openshift-service-mesh/istio-cni-rhel8 as a component of OpenShift Service Mesh 2; rhacm2/kube-rbac-proxy-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhacm2/thanos-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; advanced-cluster-security/rhacs-main-rhel8 as a component of Red Hat Advanced Cluster Security 3; osbuild-composer as a component of Red Hat Enterprise Linux 8; osbuild-composer-core as a component of Red Hat Enterprise Linux 8; osbuild-composer-dnf-json as a component of Red Hat Enterprise Linux 8; osbuild-composer-worker as a component of Red Hat Enterprise Linux 8; osbuild-composer.src as a component of Red Hat Enterprise Linux 8; osbuild-composer as a component of Red Hat Enterprise Linux 9; osbuild-composer-core as a component of Red Hat Enterprise Linux 9; osbuild-composer-dnf-json as a component of Red Hat Enterprise Linux 9; osbuild-composer-worker as a component of Red Hat Enterprise Linux 9; osbuild-composer.src as a component of Red Hat Enterprise Linux 9; openshift4/ose-kube-rbac-proxy as a component of Red Hat OpenShift Container Platform 4; devspaces/traefik-rhel8 as a component of Red Hat OpenShift Dev Spaces · Fixed: openshift4/ose-thanos-rhel8@sha256:8f0d9b4e7b1f8de6ff888808c929492c86c07ec8283c0c98c6e5dd9909a40b4b_ppc64le as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:9f32c356b85c2b798a74d4f35fb2a1af0ddf55136cb8f7659261f38df75af67a_arm64 as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:ac3558b2758c283c355f30b1255793f1363b86c199569de55a6e599a39135b1f_amd64 as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:d28afbbe89d5ccb4789188d3a42fcffc9d00b6293c80d2072fa8db41a7183568_s390x as a component of Red Hat OpenShift Container Platform 4.13; mta/mta-hub-rhel9@sha256:5cc1613cb869bab75faa5ea2798ab5f34238192b397d3c942789b4242a8a815a_amd64 as a component of MTA 6.2 for RHEL 8
After
cli as a component of OpenShift Serverless; knative-eventing as a component of OpenShift Serverless; knative-serving as a component of OpenShift Serverless; servicemesh as a component of OpenShift Service Mesh 2.1; servicemesh-cni as a component of OpenShift Service Mesh 2.1; servicemesh-pilot-agent as a component of OpenShift Service Mesh 2.1; servicemesh-pilot-discovery as a component of OpenShift Service Mesh 2.1; servicemesh.src as a component of OpenShift Service Mesh 2.1; openshift-service-mesh/istio-cni-rhel8 as a component of OpenShift Service Mesh 2; rhacm2/kube-rbac-proxy-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; rhacm2/thanos-rhel9 as a component of Red Hat Advanced Cluster Management for Kubernetes 2; advanced-cluster-security/rhacs-main-rhel8 as a component of Red Hat Advanced Cluster Security 3; osbuild-composer as a component of Red Hat Enterprise Linux 8; osbuild-composer-core as a component of Red Hat Enterprise Linux 8; osbuild-composer-dnf-json as a component of Red Hat Enterprise Linux 8; osbuild-composer-worker as a component of Red Hat Enterprise Linux 8; osbuild-composer.src as a component of Red Hat Enterprise Linux 8; osbuild-composer as a component of Red Hat Enterprise Linux 9; osbuild-composer-core as a component of Red Hat Enterprise Linux 9; osbuild-composer-dnf-json as a component of Red Hat Enterprise Linux 9; osbuild-composer-worker as a component of Red Hat Enterprise Linux 9; osbuild-composer.src as a component of Red Hat Enterprise Linux 9; openshift4/ose-kube-rbac-proxy-rhel9 as a component of Red Hat OpenShift Container Platform 4; devspaces/traefik-rhel8 as a component of Red Hat OpenShift Dev Spaces · Fixed: openshift4/ose-thanos-rhel8@sha256:8f0d9b4e7b1f8de6ff888808c929492c86c07ec8283c0c98c6e5dd9909a40b4b_ppc64le as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:9f32c356b85c2b798a74d4f35fb2a1af0ddf55136cb8f7659261f38df75af67a_arm64 as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:ac3558b2758c283c355f30b1255793f1363b86c199569de55a6e599a39135b1f_amd64 as a component of Red Hat OpenShift Container Platform 4.13; openshift4/ose-thanos-rhel8@sha256:d28afbbe89d5ccb4789188d3a42fcffc9d00b6293c80d2072fa8db41a7183568_s390x as a component of Red Hat OpenShift Container Platform 4.13; mta/mta-hub-rhel9@sha256:5cc1613cb869bab75faa5ea2798ab5f34238192b397d3c942789b4242a8a815a_amd64 as a component of MTA 6.2 for RHEL 8
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.