CVE-2026-29057 Details
Next.js is a React framework for building full-stack web applications. Starting in version 9.5.0 and prior to versions 15.5.13 and 16.1.7, when Next.js rewrites proxy traffic to an external backend, a crafted `DELETE`/`OPTIONS` request using `Transfer-Encoding: chunked` could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes. An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel. The vulnerability originated in an upstream library vendored by Next.js. It is fixed in Next.js 15.5.13 and 16.1.7 by updating that dependency’s behavior so `content-length: 0` is added only when both `content-length` and `transfer-encoding` are absent, and `transfer-encoding` is no longer removed in that code path. If upgrading is not immediately possible, block chunked `DELETE`/`OPTIONS` requests on rewritten routes at the edge/proxy, and/or enforce authentication/authorization on backend routes.
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Exploit prediction scoring system (EPSS) score for CVE-2026-29057
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.08 Probability of exploitation activity being observed over the next 30 days (24th percentile)
CVSS score for CVE-2026-29057
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
6.5 Medium
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
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CVE-2026-29057 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 144 25.95%
DE 78 14.05%
TR 70 12.61%
RU 34 6.13%
FR 25 4.50%
KR 24 4.32%
IN 21 3.78%
SG 13 2.34%
CN 11 1.98%
FI 10 1.80%

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CVE-2026-29057 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 366 78.04%
Government/Politics 68 14.50%
Telecommunications 22 4.69%
Manufacturing 6 1.28%
Transportation 2 0.43%
Finance 1 0.21%
Insurance 1 0.21%
Engineering 1 0.21%
Business Services 1 0.21%
Media/Entertainment 1 0.21%

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