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CVE-2026-85024— undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression

Quick assessment

Affected
undici undici
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

undici 捆绑了一个 WebSocket 客户端，其 permessage-deflate 的大小限制清理逻辑会从内部的 zlib inflate 流中移除所有监听器，包括其错误监听器，而该流在此时仍可能触发事件。当远程对端发送的压缩负载超过了内置的 128 MiB 解压缩负载上限，且其中包含一个格式错误的 DEFLATE 字节时，inflate 流会触发一个数据错误，但由于此时没有任何错误监听器，Node.js 将其视为未处理的致命错误，从而导致整个进程终止。 该漏洞可被远程且无需认证地利用，无需应用程序存在

CVSS 5.9 · Medium

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici 6.25.0< 6.28.1 affected
6.28.1 unaffected
7.28.0< 7.29.1 affected
7.29.1 unaffected
8.1.0< 8.10.2 affected
8.10.2 unaffected
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I. Basic Information for CVE-2026-85024

Vulnerability Information
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Vulnerability Title
undici vulnerable to Denial of Service via unhandled error in WebSocket permessage-deflate decompression
Source: CVE Program / CVE List V5
Vulnerability Description
undici bundles a WebSocket client whose permessage-deflate size-limit cleanup removes all listeners from the internal zlib inflate stream, including its error listener, while that stream can still emit. When a remote peer sends a compressed payload that crosses the built-in 128 MiB decompressed-payload limit and then contains a malformed DEFLATE byte, the inflate stream emits a data error with no listener attached, which Node.js treats as a fatal unhandled error and terminates the entire process. Exploitation is remote and unauthenticated, requires no application mistake, and is asymmetric, since roughly 130 KB on the wire expands past the limit and crashes the process, and reconnecting can repeat the crash. This affects undici versions from 6.25.0 up to 6.28.1, from 7.28.0 up to 7.29.1, and from 8.1.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未捕获的异常
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
undici undici 6.25.0 ~ 6.28.1 -

II. Public POCs for CVE-2026-85024

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III. Intelligence Information for CVE-2026-85024

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Vendor Advisories for CVE-2026-85024 (1)

Same Patch Batch · undici · 2026-09-04 · 11 CVEs total

CVE-2026-19534 7.5 HIGH undici vulnerable to Denial of Service via unrequested WebSocket subprotocol
CVE-2026-85152 7.4 HIGH undici vulnerable to cross-origin cache poisoning via missing origin isolation in intercep
CVE-2026-84961 7.4 HIGH undici vulnerable to TLS certificate validation bypass via dropped connect options in Bala
CVE-2026-84933 6.5 MEDIUM undici vulnerable to cross-user cookie disclosure via Set-Cookie caching in shared caches
CVE-2026-85014 5.9 MEDIUM undici vulnerable to Denial of Service via WebSocketStream unclean close
CVE-2026-18149 5.9 MEDIUM undici vulnerable to Denial of Service via orphaned RetryHandler response body
CVE-2026-84890 5.9 MEDIUM undici vulnerable to Denial of Service via unbounded decompression of compressed responses
CVE-2026-85008 3.7 LOW undici vulnerable to caching and replay of unsafe HTTP method responses
CVE-2026-84947 3.7 LOW undici vulnerable to response truncation via oversized chunked responses in the dump inter
CVE-2026-18540 3.7 LOW undici vulnerable to downstream response splitting via retry interceptor

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-248

V. Comments for CVE-2026-85024

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