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Fencer Intel
critical 10.0

CVE-2010-4508 json

The WebSockets implementation in Mozilla Firefox 4 through 4.0 Beta 7 does not properly perform proxy upgrade negotiation, which has unspec…

published 15y ago modified 4mo ago also EUVD-2010-4476

cvss
10.0
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

The WebSockets implementation in Mozilla Firefox 4 through 4.0 Beta 7 does not properly perform proxy upgrade negotiation, which has unspecified impact and remote attack vectors, related to an "inherent problem" with the WebSocket specification.

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Exploit prediction

1.27% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.