critical CVSS 9 EPSS 0.57%

CVE-2026-48937·Node.js vulnerability

A flaw in Node.js HTTP/2 server API can cause servers to keep accepting data even after sending a `GOAWAY` frame. This vulnerability affects two supported release lines: **Node.js 22** and **Node.js 24**.

Severity
critical
Software
Node.js
Fixed in
20.19.2+dfsg-1+deb13u3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.57% — higher than 46% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-48937 scores 9 on CVSS, so a successful attack would be serious — but at 0.57%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

Until: 20.19.2+dfsg-1+deb13u3

Fixed in: 20.19.2+dfsg-1+deb13u3

How to fix this CVE

Update Node.js to version 20.19.2+dfsg-1+deb13u3 or later to patch the HTTP/2 server vulnerability that allows continued data acceptance after GOAWAY frame transmission. This critical issue can lead to denial-of-service conditions on HTTP/2-enabled servers. Prioritize this update across all production and development environments running vulnerable Node.js versions.

sudo dnf update nodejs

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET|\* HTTP/2 followed by GOAWAY frame (0x7) in server logs without corresponding connection reset; repeated DATA frames after GOAWAY transmission; or sustained connection activity logged after GOAWAY frame ID in h2 debug logs

How to check if you are affected

  1. Check installed Node.js version: node --version or nodejs --version
  2. Verify HTTP/2 is enabled in your application: grep -r 'spdy\|http2' your-app-config/ or check for http2 module usage in application code
  3. Review server logs for repeated GOAWAY frames without connection closure: grep -i 'GOAWAY' /var/log/node-app.log or equivalent application logs
  4. Confirm patch installation by running: node --version and verifying output is >= v20.19.2 or the fixed Debian package version

FAQ

What is CVE-2026-48937?

This vulnerability exists in Node.js HTTP/2 server implementation where servers incorrectly continue processing incoming data after transmitting a GOAWAY frame, which signals connection termination. This protocol violation can be exploited to exhaust server resources and trigger denial-of-service conditions.

Is CVE-2026-48937 being actively exploited?

No, CVE-2026-48937 is not listed in the CISA Known Exploited Vulnerabilities catalog, and no public exploits are currently available. However, the critical CVSS score warrants immediate patching to prevent future exploitation.

What versions of Node.js are affected by CVE-2026-48937?

Node.js versions prior to 20.19.2+dfsg-1+deb13u3 are affected, with particular impact on Node.js 22 and 24 release lines. Check your installed version immediately to determine if remediation is required.

How do I check if my server is vulnerable to CVE-2026-48937?

Run `node --version` or `nodejs --version` and compare against 20.19.2+dfsg-1+deb13u3. Additionally, check dpkg status with `dpkg -l | grep nodejs` on Debian/Ubuntu systems to identify exact installed package versions.

Does Defensia detect CVE-2026-48937?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Node.js is installed on a monitored server, CVE-2026-48937 will appear in your dashboard with remediation steps.

Related Node.js CVEs

CVE-2026-48930CVSS 10A flaw in Node.js TLS hostname handling can cause Embedded-nul hostnames can lead to silent authority rebinding due to c-string truncation in resolver bindings. This vulnerability affects all supported release lines: **Node.js 22**, **Node.js 24**, and **Node.js 26**.
CVE-2026-21636CVSS 10A flaw in Node.js's permission model allows Unix Domain Socket (UDS) connections to bypass network restrictions when `--permission` is enabled. Even without `--allow-net`, attacker-controlled inputs (such as URLs or socketPath options) can connect to arbitrary local sockets via net, tls, or undici/fetch. This breaks the intended security boundary of the permission model and enables access to privileged local services, potentially leading to privilege escalation, data exposure, or local code execution. * The issue affects users of the Node.js permission model on version v25. In the moment of this vulnerability, network permissions (`--allow-net`) are still in the experimental phase.
CVE-2025-55130CVSS 9.1A flaw in Node.js’s Permissions model allows attackers to bypass `--allow-fs-read` and `--allow-fs-write` restrictions using crafted relative symlink paths. By chaining directories and symlinks, a script granted access only to the current directory can escape the allowed path and read sensitive files. This breaks the expected isolation guarantees and enables arbitrary file read/write, leading to potential system compromise. This vulnerability affects users of the permission model on Node.js v20, v22, v24, and v25.
CVE-2026-48619CVSS 9A flaw in Node.js HTTP/2 client allows a server to send an unlimited number of ORIGIN frames, which could lead to an Out of Memory error on the client. This vulnerability affects all supported release lines: **Node.js 22**, **Node.js 24**, and **Node.js 26**.
CVE-2026-56848CVSS 9A flaw in Node.js HTTP/2 handling allows `nghttp2_session_mem_send()` to be called re-entrantly while `nghttp2_session_mem_recv()` is executing, resulting in a heap-use-after-free. This vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.

References

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