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Full vulnerability report · 2026
CVE-2026-73551High confidence

Envoy: Path normalization does not handle dot and dotdot segments with parameters

envoyproxy · envoy

Official source article: GitHub GHSA-2W8W-RFW7-8GG4 ↗. Check the applicable product and release in the original source.

5.3MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.53% 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.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs envoyproxy envoy and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-73551 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityenvoy: envoy: path normalization bypass via dot/dot-dot segments with parameters
20 fixed

The vendor explicitly identifies these products or versions as containing the fix.

  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:0b21488cd868210ed7e8cba745414e4daf40483e8cebe6058a34cbda83b11cfd_s390x as a component of Red Hat OpenShift Service Mesh 3.0
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:13c0b9cb79e8475fdc40865ba1b68997afdc03bc2ed0bc1e0ed67f581f63fb68_arm64 as a component of Red Hat OpenShift Service Mesh 3.0
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:33fec0cbbd8c276d1db10f7461adf93f4cafbf6703c184532180dea8e76c4e77_amd64 as a component of Red Hat OpenShift Service Mesh 3.0
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:d4344eb4b4c6ce9ac5219dbb2d556a3c54f82bc39358158ba8ca5d395e92457a_ppc64le as a component of Red Hat OpenShift Service Mesh 3.0
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:005a5f7c0d8dfba971609b6cffe7ff4d20ea1271ed4b7b5a99161f46d9c0f779_arm64 as a component of Red Hat OpenShift Service Mesh 3.1
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:24f10dd378af1f1cb935734efd57064881899d1d7f37333f6e7cc275b1e3a5de_s390x as a component of Red Hat OpenShift Service Mesh 3.1
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:7cf632f4760c7a97847ca2cc8fc7bbe9d5285ff2ca3ea23bd49c834542d98d68_amd64 as a component of Red Hat OpenShift Service Mesh 3.1
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:ce2ff7eed3f4692e611ada5b5a7a7e927b400618a75c38d8bfa2baecb1a9d34e_ppc64le as a component of Red Hat OpenShift Service Mesh 3.1
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:55a523deb053cfbce9281d3e52e52114fd925eab40905b8a7597871eb0904415_ppc64le as a component of Red Hat OpenShift Service Mesh 3.2
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:57f73171450c78cb3ca21608209c1eb668159e58b0b39887f896f3ca1e58d64c_amd64 as a component of Red Hat OpenShift Service Mesh 3.2
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:5bf9f6dafcc666a4a3a232ce892e1d51fc07d2bc8110538457577318f0364788_s390x as a component of Red Hat OpenShift Service Mesh 3.2
  • registry.redhat.io/openshift-service-mesh/istio-proxyv2-rhel9@sha256:d4e96e5d7cd3baaa9dbc6304a7e199c33fe212389b55f1307f5a446efb9ae15f_arm64 as a component of Red Hat OpenShift Service Mesh 3.2
Summary
A flaw was found in Envoy. This vulnerability allows a remote attacker to bypass path-based access controls by sending requests with parameters inside dot and dot-dot URL path segments. Because Envoy fails to properly normalize these path segments, backend applications and access-control filters may interpret the requested path differently, potentially granting unauthorized access to protected resources.
Remediation
See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
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-2026-84119

No EUVD known-exploited evidence

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

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
5.3 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

What

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Why

The product defines policy namespaces and makes authorization decisions based on the assumption that a URL is canonical. This can allow a non-canonical URL to bypass the authorization.

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

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Why

The product defines policy namespaces and makes authorization decisions based on the assumption that a URL is canonical. This can allow a non-canonical URL to bypass the authorization.

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.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Use of Non-Canonical URL Paths for Authorization Decisions → 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-647 ↗

CWE-647: Use of Non-Canonical URL Paths for Authorization Decisions. The product defines policy namespaces and makes authorization decisions based on the assumption that a URL is canonical. This can allow a non-canonical URL to bypass the authorization.

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:L/I:N/A:N

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.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ANoneAvailability impact: No direct loss is represented by this metric.
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.
NetworkUnauthenticatedCWE-647
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-84119Official EUVD mapping

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy's URL normalization does not recognize dot and dotdot path segments when they carry semicolon parameters. A request such as /user/..;foo=bar/admin is therefore not canonicalized to /admin even when path normalization is enabled. If an upstream interprets the segment according to RFC 3986 while Envoy applies routing or RBAC to the uncollapsed path, a remote client can cause path confusion and bypass path-based security policy. The relevant scope boundary is that the security consequence depends on a downstream/upstream path interpretation mismatch or a path-based Envoy decision. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.

Official EUVD record ↗
JVN iPedia · Japanese · JVNDB-2026-036614Envoy ProxyのEnvoyにおける認可判断のための非正規化 URL パスの使用に関する脆弱性

Envoyはクラウドネイティブアプリケーション向けに設計されたオープンソースのエッジおよびサービスプロキシです。バージョン1.36.10、1.37.6、1.38.4、1.39.1以前のEnvoyでは、URL正規化時にセミコロン付きのパスセグメント（ドット「.」およびドットドット「..」を含む）を認識しませんでした。例えば、/user/..;foo=bar/admin のようなリクエストは、パス正規化が有効でも /admin に正規化されません。アップストリームがRFC 3986に従ってセグメントを解釈し、Envoyが正規化されていないパスに対してルーティングやRBACを適用すると、リモートクライアントはパスの混乱を引き起こし、パスベースのセキュリティポリシーを回避することが可能になります。この問題のセキュリティ上の影響範囲は、ダウンストリームとアップストリームのパス解釈の不一致、またはEnvoyがパスベースの判断を行った場合に依存します。この問題はバージョン1.36.10、1.37.6、1.38.4、および1.39.1で修正されています。

Official advisory ↗
03

Patch and workaround

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.
Patch available
Affected
envoy: 1.38.0, < 1.38.4, 1.39.0, < 1.39.1, < 1.36.10, 1.37.0, < 1.37.6
Fixed
Action
See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
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 21 Sept 2026 · Last source change 28 Sept 2026, 20:41 UTC · CWE-647 · Use of Non-Canonical URL Paths for Authorization Decisions

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-22
European sourceENISA EUVD · EUVD-2026-84119
Product sourceCNA
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: github.com/28b6d60a6d96edeece121cac5be701eb46cc7f24; removed remediation: access.redhat.com/CVE-2026-73551.
    Before
    patch: github.com/28b6d60a6d96edeece121cac5be701eb46cc7f24 · patch: github.com/d40a68b0a30a003c4e0a9fd3af637f828b52c37b · patch: github.com/e9d6c329f9a3ff19432bf39b60c601df7e3eda33 · 3 more references
    After
    patch: github.com/28b6d60a6d96edeece121cac5be701eb46cc7f24 · patch: github.com/d40a68b0a30a003c4e0a9fd3af637f828b52c37b · patch: github.com/e9d6c329f9a3ff19432bf39b60c601df7e3eda33 · 3 more references
    security-advisories@github.com ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added patch: github.com/28b6d60a6d96edeece121cac5be701eb46cc7f24; added patch: github.com/d40a68b0a30a003c4e0a9fd3af637f828b52c37b; removed remediation: access.redhat.com/CVE-2026-73551; 4 further additions.
    Before
    remediation: access.redhat.com/CVE-2026-73551
    After
    patch: github.com/28b6d60a6d96edeece121cac5be701eb46cc7f24 · patch: github.com/d40a68b0a30a003c4e0a9fd3af637f828b52c37b · patch: github.com/e9d6c329f9a3ff19432bf39b60c601df7e3eda33 · 3 more references
    security-advisories@github.com ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
    After
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · 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.
    CNA ↗
  4. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: access.redhat.com/CVE-2026-73551.
    Before
    remediation: access.redhat.com/CVE-2026-73551
    After
    no authoritative guidance recorded
    CNA ↗
  5. Affected versionsThe structured affected or fixed version information changed.
    Before
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
    After
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  6. Remediation statusRemediation status changed from Patch available to Awaiting fix.
    Before
    Patch available
    After
    Awaiting fix
    CNA ↗
  7. Affected versionsThe structured affected or fixed version information changed.
    Before
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · 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
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
    Red Hat Product Security ↗
  8. Affected versionsThe structured affected or fixed version information changed.
    Before
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
    Red Hat Product Security ↗
  9. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  10. ENISA EUVD mappingEUVD-2026-84119 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-84119"}
    ENISA EUVD ↗
  11. Vendor guidanceAuthoritative vendor guidance changed: removed remediation: access.redhat.com/CVE-2026-73551.
    Before
    remediation: access.redhat.com/CVE-2026-73551
    After
    no authoritative guidance recorded
    CNA ↗
  12. Affected versionsThe structured affected or fixed version information changed.
    Before
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: See Red Hat OpenShift Service Mesh 3.0.15 documentation at https://docs.redhat.com/en/documentation/red_hat_openshift_service_mesh/3.0
    After
    envoy: < 1.36.10, >= 1.37.0, < 1.37.6, >= 1.38.0, < 1.38.4, >= 1.39.0, < 1.39.1 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  13. Remediation statusRemediation status changed from Patch available to Awaiting fix.
    Before
    Patch available
    After
    Awaiting fix
    CNA ↗
  14. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-84119↗Red Hat Product Security security advisory↗CVE authority or vendor reference · GitHub GHSA-2W8W-RFW7-8GG4↗Patch or update reference↗Patch or update reference↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
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.
Free version - for non-commercial use only.CVE-2026-73551 · cve.blacktree.nl