Bug ID 597797: Allow users to disable enforcement of RFC 7507 Fallback SCSV

Last Modified: May 29, 2024

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
11.5.1 HF2, 11.5.1 HF3, 11.5.1 HF4, 11.5.1 HF5, 11.5.1 HF6, 11.5.1 HF7, 11.5.1 HF8, 11.5.1 HF9, 11.5.1 HF10, 11.5.1 HF11, 11.5.2 HF1, 11.5.3 HF1, 11.5.3 HF2, 11.5.4 HF1, 11.5.4 HF2, 11.5.4 HF3, 11.5.4 HF4, 12.0.0, 12.0.0 HF1, 12.1.0 HF1, 12.0.0 HF2, 12.1.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.1 HF1, 12.1.1 HF2

Fixed In:
13.0.0, 12.1.2 HF1, 11.6.1 HF2

Opened: Jun 07, 2016

Severity: 3-Major

Related Article: K78449695


When RFC 7507 (fallback SCSV) was implemented, some BIG-IP administrators found their TLS/SSL clients were incompatible and could no longer connect to the BIG-IP system.


Inability to support connections from older TLS/SSL clients that are unable to use the more recent (and more secure) TLS/SSL protocols.


Client software that attempts to connect to a virtual server using an older, less secure version of the TLS/SSL protocol, for instance, TLS 1.0.


There is no workaround.

Fix Information

When SSL.fallback_SCSV is set to disable, the RFC 7507 implementation will be disabled, though it must be acknowledged that this introduces a security hole when negotiating SSLv3.

Behavior Change

When RFC 7507 was implemented, some BIG-IP administrators found that their SSL clients were incompatible. This change introduces a bigdb variable (SSL.fallback_SCSV) to disable this.

Guides & references

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