CVE-2026-45109VulnerabilityPublished 11 May 2026Updated 4 Nov 2026

Next.js has a Middleware / Proxy bypass in App Router applications via segment-prefetch routes - Incomplete Fix

Affects nextSource GCVE Database

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Mentioned vulnerabilities

CVE-2026-44575

Authoritative record:CVE-2026-45109· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 15.5.18 soon.

Data as of 4 Nov 2026, 04:27 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Sources agree

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5
ADP (redhat-SADP)	CVSS 3.1	7.5

Patch: Available – fixed in 15.5.18, 16.2.6

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade next to 15.5.18; next to 16.2.6.

Patches and advisories

Affected software

Product	Affected	Fixed in
npmnext	Affected >=15.2.0 <15.5.18	Fixed in 15.5.18
npmnext	Affected >=16.0.0 <16.2.6	Fixed in 16.2.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and should be applied by upgrading Next.js to versions 15.5.18 or later in the 15.x series, or 16.2.6 or later in the 16.x series. Red Hat has released security advisories with errata providing fixes for this vulnerability. Users should apply these official updates promptly to remediate the issue. No additional mitigation steps are indicated beyond applying the patch.

Description

A vulnerability in Next.js App Router applications allows middleware or proxy bypass via segment-prefetch routes. This issue is an incomplete fix of CVE-2026-44575, specifically affecting middleware.ts when used with Turbopack. The vulnerability can lead to information disclosure due to middleware bypass. It affects Next.js versions from 15.2.0 up to but not including 15.5.18, and from 16.0.0 up to but not including 16.2.6. A patch is available in versions 15.5.18 and 16.2.6.

Impact

The vulnerability allows an attacker to bypass middleware protections in Next.js App Router applications, potentially leading to unauthorized information disclosure. The issue specifically affects middleware.ts files when used with Turbopack, meaning that the previous fix for CVE-2026-44575 was incomplete. The confidentiality of protected content can be compromised, but there is no impact on integrity or availability.

CWE-288Authentication Bypass Using an Alternate Path or Channel (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
The product requires authentication, but the product has an alternate path or channel that does not require authentication.
Architecture and Design
Funnel all access through a single choke point to simplify how users can access a resource. For every access, perform a check to determine if the user has permissions to access the resource.
OWASP Cheat Sheets
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V1.2.3 (opens in a new tab)
V1.2.2 (opens in a new tab)
V1.2.4 (opens in a new tab)
Attack patterns
Directory Indexing (opens in a new tab)
Exploitation of Thunderbolt Protection Flaws (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-358Improperly Implemented Security Check for Standard (opens in a new tab)
Base weakness
The product does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique.

References

Community reviews

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Exploitation evidence

What to do

Patches and advisories

Affected software

Description

AI analysisMachine-generated, updated 4 Nov 2026, 04:27 UTC

WeaknessesCWE-288, CWE-358

Technical details

References

Community reviews

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