Security readout for executives and security teams
Plain-English summary
A flaw in self-hosted Next.js applications lets an outside attacker trick the server into making requests on their behalf. That means a business's web server could be manipulated to reach internal systems or cloud metadata services it should never expose. Vercel-hosted sites are not affected, but any team running the built-in Node.js server on their own infrastructure should treat this as urgent.
Executive priority
High priority for teams self-hosting Next.js. Schedule patching within the current change window; the flaw is remotely exploitable without authentication and can pivot into internal systems or steal cloud credentials. If all Next.js properties run on Vercel, no action is required, but this should be confirmed in writing by the platform owner.
Technical view
Next.js versions 13.4.13 up to 15.5.16, and 16.0.0 up to 16.2.5, mishandle WebSocket upgrade requests in the built-in Node.js server, resulting in server-side request forgery (CWE-918). A crafted upgrade request can cause the server to proxy traffic to attacker-chosen internal or external destinations, including cloud instance metadata endpoints. CVSS 8.6 (AV:N/AC:L/PR:N/UI:N/S:C/C:H). Fixed in 15.5.16 and 16.2.5. Vercel-hosted deployments are not affected.
Likely exposure
Any self-hosted Next.js deployment on affected versions using the built-in Node.js server is exposed. Cloud-hosted workloads (AWS, GCP, Azure) are especially at risk because SSRF to metadata services can leak instance credentials. Vercel-hosted deployments are explicitly out of scope per the advisory.
Exploitation context
No unauthenticated exploitation, KEV listing, or public proof-of-concept is cited in the source bundle. The vulnerability requires no privileges or user interaction and is network-reachable, so exposure is broad wherever affected self-hosted instances face the internet. Red Hat has issued vendor advisories (RHSA-2026:37272, RHSA-2026:34608), indicating downstream patch tracking is active.
Researcher notes
CWE-918 SSRF triggered via WebSocket upgrade handling in the built-in Node.js server. CVSS scope-changed (S:C) with confidentiality-only impact reflects credential and internal-service disclosure rather than data tampering. Affected version windows are non-contiguous — 13.4.13 through pre-15.5.16, and 16.0.0 through pre-16.2.5 — so 15.x releases at or above 15.5.16 are safe and 16.x below 16.2.5 remain vulnerable. No public PoC or KEV entry noted as of 2026-07-10.
Mitigation direction
- Upgrade Next.js to 15.5.16 (13.4.13–15.x branch) or 16.2.5 (16.x branch) on all self-hosted deployments.
- Apply Red Hat errata RHSA-2026:37272 and RHSA-2026:34608 where Red Hat packages are in use.
- Restrict or block outbound egress from Next.js hosts to internal ranges and cloud metadata IPs (e.g., 169.254.169.254).
- Enforce IMDSv2 or equivalent hardened metadata access on cloud instances hosting Next.js.
- Inspect reverse proxies and WAFs for WebSocket upgrade filtering until patched.
- Confirm Vercel-hosted properties require no action per the GHSA advisory.
Validation and detection
- Inventory all Next.js deployments and record versions against affected ranges 13.4.13–<15.5.16 and 16.0.0–<16.2.5.
- Confirm which deployments use the built-in Node.js server versus Vercel hosting.
- After upgrade, verify package.json and lockfiles reflect 15.5.16 or 16.2.5 and redeploy.
- Review egress logs for unexpected WebSocket upgrade traffic or requests to metadata endpoints.
- Validate cloud metadata service is not reachable from the Next.js runtime after mitigation.
- Track Red Hat CSAF/VEX feed and GHSA-c4j6-fc7j-m34r for advisory updates.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-918: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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 lookupCloud metadata behavior lookup
The CVE wording references SSRF or metadata access, so cloud discovery and credential material review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-44578 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
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.
SSVC decision data
CVSS vector scores
2 official scoresWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N3.94GitHub_MCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N3.94redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Base CVSS 3.1 score
8.6HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-13T18:01:13.729Z: Reported to Red Hat.
- 2026-05-13T17:01:38.942Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/vercel/next.js/security/advisories/GHSA-c4j6-fc7j-m34rCVE reference, GitHub_M · x_refsource_CONFIRM
- https://access.redhat.com/security/cve/CVE-2026-44578CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2477187CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44578.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:37272CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:34608CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Server-Side Request Forgery (SSRF)
Server-Side Request Forgery (SSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.