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Fencer Intel
critical 9.1

CVE-2021-46825 json

Symantec Advanced Secure Gateway (ASG) and ProxySG are susceptible to an HTTP desync vulnerability.

published 4y ago modified 4mo ago also EUVD-2021-33480

cvss
9.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.7%
EPSS 1.7% chance of exploitation in 30 days, percentile 77%
public exploits
0
none known

Summary

Symantec Advanced Secure Gateway (ASG) and ProxySG are susceptible to an HTTP desync vulnerability. When a remote unauthenticated attacker and other web clients communicate through the proxy with the same web server, the attacker can send crafted HTTP requests and cause the proxy to forward web server responses to unintended clients. Severity/CVSSv3: High / 8.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

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Exploit prediction

1.68% chance of exploitation in the next 30 days, higher than 77% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N

Affected products

  • n/a Advance Secure Gateway and ProxySG

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

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.