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CVE Record

CVE-2026-44575: Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes

Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.16 and 16.2.5, App Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted .rsc and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check. This vulnerability is fixed in 15.5.16 and 16.2.5.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Affected Next.js applications may expose protected page content because certain prefetch-related URL variants can bypass middleware or proxy authorization checks. The issue is remotely reachable without credentials or user interaction when the vulnerable application design is present. Confidential information is the primary risk; the supplied evidence does not indicate data modification or service disruption.

Executive priority

Prioritize rapid remediation for internet-facing applications that place confidential content behind middleware or proxy checks. Upgrade affected releases promptly and validate every protected App Router route. Lower priority is reasonable only after confirming the application is outside the affected versions or does not depend on the vulnerable authorization pattern.

Technical view

CVE-2026-44575 affects Next.js App Router versions 15.2.0 through 15.5.15 and 16.0.0 through 16.2.4. Specially crafted .rsc and segment-prefetch routes may resolve to a protected page without matching its intended middleware or proxy rule. CVSS 3.1 is 7.5, reflecting unauthenticated, low-complexity network access and high confidentiality impact.

Likely exposure

Exposure is limited to affected Next.js versions using the App Router where authorization depends on middleware or proxy matching. Applications using other versions, architectures, or independent server-side authorization may not be vulnerable. Internet-facing protected routes and sensitive rendered content increase business risk.

Exploitation context

The supplied record marks this CVE as absent from KEV and provides no evidence of active exploitation. Its network reachability, low complexity, and lack of required credentials make vulnerable deployments attractive targets, but real-world exploit prevalence is unknown from the available sources.

Researcher notes

The weakness is an authorization-check bypass caused by alternate transport-specific routing forms reaching the same resource without equivalent middleware matching. It maps to CWE-288 and CWE-551. The supplied CVSS vector indicates confidentiality impact only. Whether returned content exposes usable secrets depends on application-specific rendering and downstream authorization controls.

Mitigation direction

  • Upgrade Next.js 15.x deployments to 15.5.16 or later.
  • Upgrade Next.js 16.x deployments to 16.2.5 or later.
  • Confirm sensitive data has authorization enforcement independent of route-matching behavior.
  • Review the Next.js advisory and applicable Red Hat guidance before using temporary mitigations.

Validation and detection

  • Inventory deployed Next.js versions, including build artifacts and lockfiles.
  • Identify App Router applications using middleware or proxy rules for authorization.
  • Verify protected content remains inaccessible across framework-generated prefetch route variants.
  • Review access logs for unusual .rsc or segment-prefetch requests targeting protected pages.
  • Run authorization regression tests after upgrading.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-288: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-551: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-44575 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-44575Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPnext.js: Next.js: Unauthorized access to protected content via middleware bypass
other:Red Hat severity ratingcvssV3_1
  • 2026-05-13T18:01:17.168Z: Reported to Red Hat.
  • 2026-05-13T16:54:39.455Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
vercelnext.js>= 16.0.0, < 16.2.5, >= 15.2.0, < 15.5.16Listed
Weakness

CWE details

CWE-288CWE-551

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.