CVE-2026-18149 · GHSA-pmjh-fq2x-6v4x
undici vulnerable to Denial of Service via orphaned RetryHandler response body
- Risk score
- 46/100
- CVSS
- 5.9 v3.1
- Exploit chance (30 days)
- 0.4%
- Published
- 29 Sep 2026
Open in the live forecast Today's forecast
What to know
- What it is
- undici's RetryHandler can leave a response body pending indefinitely. When a retried request receives a non-retryable response after a truncated one, the original response.body held by the application is never settled, so reads such as response.body.text() hang and bodyTimeout does not fire. A malicious server can rep…
- Affected
- undici (npm) >= 7.11.0, < 7.29.1; undici (npm) >= 8.0.0, < 8.10.2
- Fix
- Upgrade undici to 7.29.1 or 8.10.2 (whichever matches your release line) or later.
- Exploitation
- No known exploitation
Story map
At a glance
undici: Amber, patch this week. The undici WebSocket client throws an uncaught TypeError during the opening handshake when a server's 101 response includes a Sec-WebSocket-Protocol header that the client never requested. The throw occurs in a queueMicrotask callback with no surrounding try/catch, so it propagates as an uncaught exception and termina…
The flaws
- CVE-2026-18149: Undici vulnerable to Denial of Service via orphaned RetryHandler response body (CVSS 5.9 · EPSS 0%)
- CVE-2026-19534: Undici vulnerable to Denial of Service via unrequested WebSocket subprotocol (CVSS 7.5 · EPSS 0%)
- CVE-2026-85152: Undici vulnerable to cross-origin cache poisoning via missing origin isolation in interceptors (CVSS 7.4 · EPSS 0%)
- CVE-2026-84961: Undici vulnerable to TLS certificate validation bypass via dropped connect options in BalancedPool (CVSS 7.4 · EPSS 0%)
The fix
Fix: Upgrade undici to 6.28.1 or 7.29.1 or 8.10.2 (whichever matches your release line) or later.
Who is exposed: undici (npm) >= 6.7.0, < 6.28.1; undici (npm) >= 7.0.0, < 7.29.1; undici (npm) >= 8.0.0, < 8.10.2
Where it stands
- No known exploitation
Connects to
- Same weakness: CWE-772 (CWE-772). 9 other warnings in 30 days
Why it is Yellow
- CVSS 5.9 medium
- On your watchlist: npm
Affected packages
| Package | Ecosystem | Vulnerable | Fixed in |
|---|---|---|---|
| undici | npm | >= 7.11.0, < 7.29.1 | 7.29.1 |
| undici | npm | >= 8.0.0, < 8.10.2 | 8.10.2 |
References
- https://github.com/advisories/GHSA-pmjh-fq2x-6v4x
- https://github.com/nodejs/undici/security/advisories/GHSA-pmjh-fq2x-6v4x
- https://nvd.nist.gov/vuln/detail/CVE-2026-18149
- https://github.com/nodejs/undici/commit/3c6726599cea8646384dde846c97d630da472a74
- https://github.com/nodejs/undici/commit/e905b5b87e6953bcc542af90557b2fee5b7b5974
- https://hackerone.com/reports/3892751
- https://cna.openjsf.org/security-advisories.html
- https://github.com/nodejs/undici/releases/tag/v7.29.1
- https://github.com/nodejs/undici/releases/tag/v8.10.2
- https://github.com/advisories/GHSA-pmjh-fq2x-6v4x
Original description
### Impact undici's `RetryHandler` can leave a response body pending indefinitely. When a retried request receives a non-retryable response after a truncated one, the original `response.body` held by the application is never settled, so reads such as `response.body.text()` hang and `bodyTimeout` does not fire. A malicious server can repeat this to accumulate pending promises and streams, leading to denial of service. ### Patches Patched in undici v7.29.1 and v8.10.2. ### Workarounds Impose an independent request deadline and destroy the response body when it expires. `bodyTimeout` alone does not prevent this.
Last activity 29 Sep 2026. Patch Forecast updates every hour.