StackPrism

npm package

undici 6.21.0 vulnerabilities, and the version that fixes all of them

undici 6.21.0 has 17 known vulnerabilities (5 rated high or critical); 6.28.1 fixes all of them.

npm (opens in a new tab) describes it as “An HTTP/1.1 client, written from scratch for Node.js”

Known vulnerabilities
17
5 rated high or critical
Released
Nov 13, 2024
Latest is 8.12.2
Downloads last week
161.6K
Under 1% of undici downloads
Licence
MIT
OpenSSF Scorecard
8.1/10
nodejs/undici (opens in a new tab)
Dependencies
None
Resolved by deps.dev

What to upgrade to

6.28.1 is the closest release with no known vulnerabilities.

  • 6.28.1Upgrade to this

    Fixes all 17 known vulnerabilities. Released Sep 4, 2026.

    No known vulnerabilities

  • 6.29.1

    Newest 6.x release. Released Oct 15, 2026.

    No known vulnerabilities

  • 8.12.2

    Latest release. Released Oct 15, 2026.

    No known vulnerabilities

6.28.1 came out on Sep 4, 2026. A coding agent trained before then doesn’t know it exists, so it may suggest an older release. AI knowledge cutoff dates

Hand the fix to your coding agent

One task with the upgrade, the file to change and why. Paste it into Claude Code, Cursor or Codex.

Findings

Every advisory for undici 6.21.0

Known exploited first (CISA KEV), then by how likely they are to be exploited (FIRST EPSS), then by severity. Each id links to its OSV.dev record.

  1. CriticalCVE-2026-1526 on OSV.dev (opens in a new tab)GHSA-vrm6-8vpv-qv8qEPSS: top 34%

    Undici has Unbounded Memory Consumption in WebSocket permessage-deflate Decompression

    Fixed in 6.24.0. Published Mar 13, 2026.

  2. CriticalCVE-2026-2229 on OSV.dev (opens in a new tab)GHSA-v9p9-hfj2-hcw8EPSS: top 42%

    Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation

    Fixed in 6.24.0. Published Mar 13, 2026.

  3. CriticalCVE-2026-12151 on OSV.dev (opens in a new tab)GHSA-vxpw-j846-p89qEPSS: top 45%

    undici WebSocket client vulnerable to denial of service via fragment count bypass

    Fixed in 6.27.0. Published Jun 19, 2026.

  4. WarningCVE-2025-22150 on OSV.dev (opens in a new tab)GHSA-c76h-2ccp-4975EPSS: top 46%

    Use of Insufficiently Random Values in undici

    Fixed in 6.21.1. Published Jan 21, 2025.

  5. WarningCVE-2026-1525 on OSV.dev (opens in a new tab)GHSA-2mjp-6q6p-2qxmEPSS: top 58%

    Undici has an HTTP Request/Response Smuggling issue

    Fixed in 6.24.0. Published Mar 13, 2026.

  6. CriticalCVE-2026-1528 on OSV.dev (opens in a new tab)GHSA-f269-vfmq-vjvjEPSS: top 59%

    Undici: Malicious WebSocket 64-bit length overflows parser and crashes the client

    Fixed in 6.24.0. Published Mar 13, 2026.

  7. WarningCVE-2026-22036 on OSV.dev (opens in a new tab)GHSA-g9mf-h72j-4rw9EPSS: top 62%

    Undici has an unbounded decompression chain in HTTP responses on Node.js Fetch API via Content-Encoding leads to resource exhaustion

    Fixed in 6.23.0. Published Jan 14, 2026.

  8. CriticalCVE-2026-19534 on OSV.dev (opens in a new tab)GHSA-rfgv-xxqx-mfg5EPSS: top 69%

    undici vulnerable to Denial of Service via unrequested WebSocket subprotocol

    Fixed in 6.28.1. Published Sep 29, 2026.

  9. LowCVE-2025-47279 on OSV.dev (opens in a new tab)GHSA-cxrh-j4jr-qwg3EPSS: top 75%

    undici Denial of Service attack via bad certificate data

    Fixed in 6.21.2. Published May 15, 2025.

  10. WarningCVE-2026-9679 on OSV.dev (opens in a new tab)GHSA-p88m-4jfj-68fvEPSS: top 76%

    undici vulnerable to HTTP header injection via Set-Cookie percent-decoding

    Fixed in 6.27.0. Published Jun 19, 2026.

  11. WarningCVE-2026-1527 on OSV.dev (opens in a new tab)GHSA-4992-7rv2-5pvqEPSS: top 81%

    Undici has CRLF Injection in undici via `upgrade` option

    Fixed in 6.24.0. Published Mar 13, 2026.

  12. LowCVE-2026-6733 on OSV.dev (opens in a new tab)GHSA-35p6-xmwp-9g52EPSS: top 83%

    undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse

    Fixed in 6.27.0. Published Jun 19, 2026.

  13. LowCVE-2026-18540 on OSV.dev (opens in a new tab)GHSA-r53p-7pc4-xj5rEPSS: top 87%

    undici vulnerable to downstream response splitting via retry interceptor

    Fixed in 6.28.1. Published Sep 29, 2026.

  14. LowCVE-2026-11525 on OSV.dev (opens in a new tab)GHSA-g8m3-5g58-fq7mEPSS: top 87%

    undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

    Fixed in 6.27.0. Published Jun 19, 2026.

  15. WarningCVE-2026-15157 on OSV.dev (opens in a new tab)GHSA-m8rv-5g2x-5cg5EPSS: top 92%

    undici vulnerable to CRLF Injection via blob-like body 'type' property

    Fixed in 6.28.0. Published Aug 3, 2026.

  16. WarningCVE-2026-16729 on OSV.dev (opens in a new tab)GHSA-v3r7-h72x-cjcmEPSS: top 92%

    undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields

    Fixed in 6.28.0. Published Aug 3, 2026.

  17. WarningCVE-2026-16728 on OSV.dev (opens in a new tab)GHSA-8xcm-r25x-g524EPSS: top 94%

    undici vulnerable to downstream response desynchronization via retry interceptor

    Fixed in 6.28.0. Published Aug 3, 2026.

Who is still on a vulnerable undici

51% of last week’s 217.5M undici downloads went to versions with known vulnerabilities.

From npm’s per-version download counts for the last 7 days, each version checked against OSV.dev. The versions checked cover over 99% of downloads.

Is undici the only one?

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How this page is checked

StackPrism asks OSV.dev which advisories affect exactly undici 6.21.0, merges duplicates filed under several ids, and ranks them with CISA’s Known Exploited Vulnerabilities list and FIRST EPSS. Release dates and deprecation come from deps.dev and npm. No AI writes this page: every sentence comes from that data, refreshed every few hours.

Last checked against npm, OSV.dev, deps.dev, CISA KEV and FIRST EPSS.