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Medium

Use of Insufficiently Random Values in undici

  • Disclosed: 21.01.2025
  • Updated: 11.10.2026 10:22

Impact

Undici fetch() uses Math.random() to choose the boundary for a multipart/form-data request. It is known that the output of Math.random() can be predicted if several of its generated values are known.

If there is a mechanism in an app that sends multipart requests to an attacker-controlled website, they can use this to leak the necessary values. Therefore, An attacker can tamper with the requests going to the backend APIs if certain conditions are met.

Patches

This is fixed in 5.28.5; 6.21.1; 7.2.3.

Workarounds

Do not issue multipart requests to attacker controlled servers.

References

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package undici >= 4.5.0, < 5.28.5, >= 6.0.0, < 6.21.1, >= 7.0.0, < 7.2.3 5.28.5, 6.21.1, 7.2.3

References

CVSS score 6.8/10
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Weakness (CWE)
CWE-330
Platform
npm
Package
undici
Disclosed
21.01.2025
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-c76h-2ccp-4975 - CC BY 4.0

Vulnerability history: undici

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (46) in the archive
Total entries
46
First → latest
06.2022 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 13
  • Medium 21
  • Low 12

Disclosures per year

Severity:
  1. undici vulnerable to Denial of Service via unrequested WebSocket subprotocol
    High · 7.5 CVE-2026-19534 >= 6.7.0, < 6.28.1, >= 7.0.0, < 7.29.1, >= 8.0.0, < 8.10.2 6.28.1, 7.29.1, 8.10.2
  2. undici vulnerable to TLS certificate validation bypass via dropped connect options in BalancedPool
    High · 7.4 CVE-2026-84961 >= 7.24.1, < 7.29.1, >= 8.0.0, < 8.10.2 7.29.1, 8.10.2
  3. undici vulnerable to cross-origin cache poisoning via missing origin isolation in interceptors
    High · 7.4 CVE-2026-85152 >= 8.10.0, < 8.10.2 8.10.2
  4. undici vulnerable to cross-user information disclosure and parse-time crash via degenerate private cache directives
    High · 7.4 CVE-2026-13697 >= 7.0.0, < 7.29.0, >= 8.0.0, < 8.9.0 7.29.0, 8.9.0
  5. undici WebSocket client vulnerable to denial of service via fragment count bypass
    High · 7.5 CVE-2026-12151 < 6.27.0, >= 7.0.0, < 7.28.0, >= 8.0.0, < 8.5.0 6.27.0, 7.28.0, 8.5.0
  6. undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse
    High · 7.5 CVE-2026-6734 >= 7.23.0, < 7.28.0, >= 8.0.0, < 8.2.0 7.28.0, 8.2.0
  7. undici vulnerable to TLS certificate validation bypass via dropped requestTls in SOCKS5 ProxyAgent
    High · 7.4 CVE-2026-9697 >= 7.23.0, < 7.28.0, >= 8.0.0, < 8.5.0 7.28.0, 8.5.0
  8. undici WebSocket client vulnerable to denial of service via cumulative fragment bypass
    High · 7.5 CVE-2026-9675 >= 8.0.0, < 8.5.0 8.5.0
  9. Undici has Unbounded Memory Consumption in WebSocket permessage-deflate Decompression
    High · 7.5 CVE-2026-1526 < 6.24.0, >= 7.0.0, < 7.24.0 6.24.0, 7.24.0
  10. Undici has Unhandled Exception in WebSocket Client Due to Invalid server_max_window_bits Validation
    High · 7.5 CVE-2026-2229 < 6.24.0, >= 7.0.0, < 7.24.0 6.24.0, 7.24.0
  11. Undici: Malicious WebSocket 64-bit length overflows parser and crashes the client
    High · 7.5 CVE-2026-1528 >= 6.0.0, < 6.24.0, >= 7.0.0, < 7.24.0 6.24.0, 7.24.0
  12. Use of Insufficiently Random Values in undici this entry
    Medium · 6.8 CVE-2025-22150 >= 4.5.0, < 5.28.5, >= 6.0.0, < 6.21.1, >= 7.0.0, < 7.2.3 5.28.5, 6.21.1, 7.2.3
  13. Regular Expression Denial of Service in Headers
    High · 7.5 CVE-2023-24807 < 5.19.1 5.19.1
  14. ProxyAgent vulnerable to MITM
    High · 7.7 CVE-2022-32210 >= 4.8.2, < 5.5.1 5.5.1

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