BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2026
CVE-2026-88007High confidence

Traefik HTTP/3 Backend NTLM Connection Reuse

traefik · traefik

Official source article: GitHub GHSA-QQJF-53CJ-PWVV ↗. Check the applicable product and release in the original source.

9.1CriticalCVSS 4.0
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, 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 0.60% 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 traefik traefik 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: Within 3 daysRemediation target: Within 90 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.

Open-source package ranges7 source-attributed ranges

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.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
Gogithub.com/traefik/traefikSEMVER: introduced 0Not statedOSV record ↗aggregator derived · 17 Sep 2026
Gogithub.com/traefik/traefik/v2SEMVER: introduced 2.11.0; fixed 2.11.572.11.57OSV record ↗aggregator derived · 17 Sep 2026
Gogithub.com/traefik/traefik/v2SEMVER: introduced 2.11.0; fixed 2.11.572.11.57OSV record ↗aggregator derived · 17 Sep 2026
Gogithub.com/traefik/traefik/v3SEMVER: introduced 3.0.0; fixed 3.7.133.7.13OSV record ↗aggregator derived · 17 Sep 2026
Gogithub.com/traefik/traefik/v3SEMVER: introduced 3.0.0; fixed 3.7.133.7.13OSV record ↗aggregator derived · 17 Sep 2026
gogithub.com/traefik/traefik/v2>= 2.11.0, < 2.11.572.11.57GitHub advisory ↗upstream repository advisory · 10 Sep 2026
gogithub.com/traefik/traefik/v3>= 3.0.0, < 3.7.133.7.13GitHub advisory ↗upstream repository advisory · 10 Sep 2026
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-2026-88007 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitygithub.com/traefik/traefik: Traefik HTTP/3 Backend NTLM Connection Reuse
4 fixed

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

  • registry.redhat.io/devspaces/traefik-rhel9@sha256:4f673d88ce055610c45123bef5c31446fdb8406d1d4969a643943f246e179c84_arm64 as a component of Red Hat OpenShift Dev Spaces 3.31
  • registry.redhat.io/devspaces/traefik-rhel9@sha256:a3213419c43bfccc2fc55d9dd0115e464bd2fd8fb4e5a400cc3880f65198e9e3_s390x as a component of Red Hat OpenShift Dev Spaces 3.31
  • registry.redhat.io/devspaces/traefik-rhel9@sha256:c51e88125ea5402efd4d6d445089fe17d3e7c719d6cab72538eea0791dd2663a_ppc64le as a component of Red Hat OpenShift Dev Spaces 3.31
  • registry.redhat.io/devspaces/traefik-rhel9@sha256:ed77f86958364fe53d8181e451581a77e242a4db791976fc7490cfcb454e589e_amd64 as a component of Red Hat OpenShift Dev Spaces 3.31
Summary
A flaw in Traefik's HTTP/3 ConnContext allows unauthenticated remote attackers to bypass authentication on backends using connection-bound NTLM or Negotiate protocols. Missing service.AddTransportOnContext calls lead to shared kerberosRoundTripper transports, enabling attackers to hijack persistent victim backend connections, read victim-only data, and impersonate victims without credentials.
Remediation
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
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-2026-75544

No EUVD known-exploited evidence

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

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
9.1 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Patch available
01

What, why and how

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

What

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

Why

The affected component does not establish the requesting party's identity reliably before granting access.

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

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

Why

The affected component does not establish the requesting party's identity reliably before granting access.

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 → Improper Authentication → 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
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-287 ↗

CWE-287: Improper Authentication. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: 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.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
NetworkUnauthenticatedCWE-287
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-75544Official EUVD mapping

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

Official EUVD record ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260916Security Bulletin 16 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 16 Sep 2026, published on 16 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-033521traefikにおける複数の脆弱性

TraefikはオープンソースのHTTPリバースプロキシおよびロードバランサーです。バージョン2.11.0から2.11.57および3.7.13までの間で、HTTP/3エントリポイントのConnContextがservice.AddTransportOnContextを呼び出さないため、kerberosRoundTripperは各フロントエンド接続専用のトランスポートではなく共有されたバックエンドトランスポートを使用していました。HTTP/3が有効で、接続に紐づくNTLMまたはNegotiate認証を使用するバックエンドとバックエンドのキープアライブがある場合、無関係のクライアントが被害者用に認証されたバックエンド接続を再利用し、被害者専用のデータを読み取り、被害者の資格情報なしでその被害者として振る舞うことが可能でした。この問題は2.11.57および3.7.13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
traefik: 3.0.0, < 3.7.13, 2.11.0, < 2.11.57
Fixed
Action
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
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.
Official vendor articles3 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

  • Release v3.7.13 · traefik/traefik · GitHub →Original publisher ↗Searchable text snapshot · Captured 2 Nov 2026Repository navigation Code Issues 681  ( 681 ) Pull requests 294  ( 294 ) Actions Projects Security and quality 89  ( 89 ) Insights More items v3.7.13 Compare Choose a tag to compare Sorry, something went wrong. Filter Loading Sorry, something went wrong. Uh oh! There was an error while loading. Please reload
  • Release v2.11.57 · traefik/traefik · GitHub →Original publisher ↗Searchable text snapshot · Captured 25 Oct 2026Repository navigation Code Issues 678  ( 678 ) Pull requests 283  ( 283 ) Actions Projects Security and quality 89  ( 89 ) Insights More items v2.11.57 Compare Choose a tag to compare Sorry, something went wrong. Filter Loading Sorry, something went wrong. Uh oh! There was an error while loading. Please reloa
  • Traefik HTTP/3 Backend NTLM Connection Reuse · Advisory · traefik/traefik · GitHub →Original publisher ↗Searchable text snapshot · Captured 25 Oct 2026Repository navigation Code Issues 678  ( 678 ) Pull requests 283  ( 283 ) Actions Projects Security and quality 89  ( 89 ) Insights More items Traefik HTTP/3 Backend NTLM Connection Reuse Critical kevinpollet published GHSA-qqjf-53cj-pwvv Sep 7, 2026 Package github.com/traefik/traefik/v2 ( Go ) Affected ver
04

Evidence and provenance

Published 10 Sept 2026 · Last source change 10 Sept 2026, 15:38 UTC · CWE-287 · Improper Authentication

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 2026-09-11
European sourceENISA EUVD · EUVD-2026-75544
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. Affected versionsThe structured affected or fixed version information changed.
    Before
    traefik: >= 2.11.0, < 2.11.57, >= 3.0.0, < 3.7.13 · 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
    traefik: >= 2.11.0, < 2.11.57, >= 3.0.0, < 3.7.13 · Fixed: Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-88007 to remediation: access.redhat.com/CVE-2026-88007.
    Before
    remediation: access.redhat.com/CVE-2026-88007
    After
    remediation: access.redhat.com/CVE-2026-88007
    Red Hat Product Security ↗
  3. Remediation statusRemediation status changed from Mitigation available to Patch available.
    Before
    Mitigation available
    After
    Patch available
    Red Hat Product Security ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    devspaces/traefik-rhel9 as a component of Red Hat OpenShift Dev Spaces
    After
    Fixed: registry.redhat.io/devspaces/traefik-rhel9@sha256:4f673d88ce055610c45123bef5c31446fdb8406d1d4969a643943f246e179c84_arm64 as a component of Red Hat OpenShift Dev Spaces 3.31; registry.redhat.io/devspaces/traefik-rhel9@sha256:a3213419c43bfccc2fc55d9dd0115e464bd2fd8fb4e5a400cc3880f65198e9e3_s390x as a component of Red Hat OpenShift Dev Spaces 3.31; registry.redhat.io/devspaces/traefik-rhel9@sha256:c51e88125ea5402efd4d6d445089fe17d3e7c719d6cab72538eea0791dd2663a_ppc64le as a component of Red Hat OpenShift Dev Spaces 3.31; registry.redhat.io/devspaces/traefik-rhel9@sha256:ed77f86958364fe53d8181e451581a77e242a4db791976fc7490cfcb454e589e_amd64 as a component of Red Hat OpenShift Dev Spaces 3.31
    Red Hat Product Security ↗
  5. BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.
    Before
    no BlackTree article
    After
    1 BlackTree article
    BlackTree editorial ↗
  6. ENISA EUVD mappingEUVD-2026-75544 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-75544"}
    ENISA EUVD ↗
  7. Vendor guidanceAuthoritative vendor guidance changed: added patch: github.com/13812; added patch: github.com/GHSA-qqjf-53cj-pwvv; 2 further additions.
    Before
    no authoritative guidance recorded
    After
    patch: github.com/13812 · patch: github.com/GHSA-qqjf-53cj-pwvv · patch: github.com/ff39c47d7459dec9cd8de63c1a4e7aa7315bdc1c · 1 more references
    security-advisories@github.com ↗
  8. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 2.11.0, < 2.11.57; >= 3.0.0, < 3.7.13 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    traefik: >= 2.11.0, < 2.11.57, >= 3.0.0, < 3.7.13 · 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 ↗
  9. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    security-advisories@github.com ↗
  10. 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
ENISA EUVD · EUVD-2026-75544↗Red Hat Product Security security advisory↗CVE authority or vendor reference · GitHub GHSA-QQJF-53CJ-PWVV↗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-2026-88007 · cve.blacktree.nl