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.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-76169High confidence
fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers
fastify · fastify
Official source article: GitHub GHSA-P68Q-WCHP-6FH7 ↗. Check the applicable product and release in the original source.
7.5HighCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productHigh technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:High, unchanged from published severity.unchanged
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
- Confirm that the asset runs fastify fastify 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.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Red Hat Product Security: 16 affected or under-investigation product states without a fixed product state in the same current advisory
Open-source package ranges2 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 package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| npmfastify | >= 4.0.0, < 5.12.2 | 5.12.2 | GitHub advisory ↗upstream repository advisory · 30 Sep 2026 |
| npmfastify | SEMVER: introduced 4.0.0; fixed 5.12.2 | 5.12.2 | OSV record ↗aggregator derived · 1 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative 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.
CVE-2026-76169 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityfastify: fastify: Authentication bypass via malformed URLs
The vendor explicitly identifies these products as affected by this CVE.
- rhelai3/bootc-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/bootc-gaudi-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/bootc-rocm-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/disk-image-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhoai/odh-core-bff-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-dashboard-operator-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-dashboard-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-agent-ops-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-automl-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-autorag-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-eval-hub-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-gen-ai-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- Summary
- A flaw was found in fastify. Malformed URLs can be routed to a custom not-found handler of a different plugin, bypassing the intended security checks. This allows an unauthenticated attacker to access and read the full response of an authentication-protected private fallback, leading to information disclosure and an authentication bypass.
- Remediation
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 16 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
fastify versions >= 4.0.0 and before 5.12.2 can route a malformed URL sent under one plugin prefix to the custom not-found handler of a different sibling plugin, and invoke it without the preHandler hook declared for that handler. The internal not-found router for encapsulated handlers dispatches malformed paths through a single shared handler pointer before URL decoding, ignoring the prefix and skipping the selected handler's normal lifecycle. An unauthenticated attacker can therefore reach an authentication-protected private fallback through an unrelated public prefix and read its full response, bypassing the authentication hook and breaking prefix encapsulation. Users should upgrade to fastify 5.12.2 or later.
What
fastify versions >= 4.0.0 and before 5.12.2 can route a malformed URL sent under one plugin prefix to the custom not-found handler of a different sibling plugin, and invoke it without the preHandler hook declared for that handler. The internal not-found router for encapsulated handlers dispatches malformed paths through a single shared handler pointer before URL decoding, ignoring the prefix and skipping the selected handler's normal lifecycle. An unauthenticated attacker can therefore reach an authentication-protected private fallback through an unrelated public prefix and read its full response, bypassing the authentication hook and breaking prefix encapsulation. Users should upgrade to fastify 5.12.2 or later.
Why
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
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
fastify versions >= 4.0.0 and before 5.12.2 can route a malformed URL sent under one plugin prefix to the custom not-found handler of a different sibling plugin, and invoke it without the preHandler hook declared for that handler. The internal not-found router for encapsulated handlers dispatches malformed paths through a single shared handler pointer before URL decoding, ignoring the prefix and skipping the selected handler's normal lifecycle. An unauthenticated attacker can therefore reach an authentication-protected private fallback through an unrelated public prefix and read its full response, bypassing the authentication hook and breaking prefix encapsulation. Users should upgrade to fastify 5.12.2 or later.
Why
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 → Authentication Bypass Using an Alternate Path or Channel → 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-288 ↗
CWE-288: Authentication Bypass Using an Alternate Path or Channel. The product requires authentication, but the product has an alternate path or channel that does not require authentication.
- 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:H/I:N/A:NCommon 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.CHighConfidentiality impact: A successful attack can cause a major 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.
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. - Fix availability varies by product
- Affected
- rhelai3/bootc-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/bootc-gaudi-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/bootc-rocm-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhelai3/disk-image-cuda-rhel9 as a component of Red Hat Enterprise Linux AI (RHEL AI) 3
- rhoai/odh-core-bff-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-dashboard-operator-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-dashboard-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-agent-ops-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-automl-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-autorag-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-eval-hub-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-gen-ai-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-maas-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-mlflow-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- rhoai/odh-mod-arch-model-registry-rhel9 as a component of Red Hat OpenShift AI (RHOAI)
- devspaces/dashboard-rhel9 as a component of Red Hat OpenShift Dev Spaces
- Fixed
- fastify: 5.12.2
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- Workaround
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official vendor articles1 stored document
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.
- fastify vulnerable to authentication bypass via malformed URLs reaching encapsulated not-found handlers · Advisory · fastify/fastify · GitHub →Original publisher ↗Searchable text snapshot · Captured 27 Sep 2026fastify / fastify Public Uh oh! There was an error while loading. Please reload this page . Notifications You must be signed in to change notification settings Fork 3k Star 37.2k Code Issues 56 Pull requests 103 Discussions Actions Security and quality 15 Insights Additional navigation options Code Iss
04
Evidence and provenance
Published 4 Sept 2026 · Last source change 4 Sept 2026, 16:20 UTC · CWE-288 · Authentication Bypass Using an Alternate Path or Channel
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-09-04
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-70988
Product sourceVendor CSAF · Red Hat Product Security
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
View recent updates ↗What changed after publication
- BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.BlackTree editorial ↗
- Before
- no BlackTree article
- After
- 1 BlackTree article
- Vendor guidanceAuthoritative vendor guidance changed: added mitigation: github.com/GHSA-p68q-wchp-6fh7.github.com ↗
- Before
- remediation: github.com/GHSA-p68q-wchp-6fh7
- After
- mitigation: github.com/GHSA-p68q-wchp-6fh7 · remediation: github.com/GHSA-p68q-wchp-6fh7
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- 4.0.0 < 5.12.2 · Fixed: 5.12.2
- After
- fastify: 4.0.0 < 5.12.2 · Fixed: fastify: 5.12.2
- ENISA EUVD mappingEUVD-2026-70988 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2026-70988"}
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
CVE published
Fixed release or patch reference recorded
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.