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CVE Request (2002): Linux TCP stack could accept invalid TCP flag combinations
From: Marcus Meissner <meissner () suse de>
Date: Fri, 3 Feb 2012 11:37:06 +0100
After a customer query likely coming from erroneous Security Scanner output,
this issue from 2002 has no CVE id yet as far as I see:
It describes a problem where firewalls might let some TCP flags combinations
pass (e.g. all with RST flag set) and the OS (e.g. Linux) stack would in turn
accept a TCP session it might not have accepted otherwise.
The protection added in Linux 2.4.20 is checking for the RST (reset) flag
when a SYN packet is received, which was I think the main attack scenario.
The relevant part of the 2.4.20 patch is:
@@ -3667,6 +3693,9 @@
+ goto discard;
if(tp->af_specific->conn_request(sk, skb) < 0)
The check still exists in current mainline git, so the issue is still fixed.
- CVE Request (2002): Linux TCP stack could accept invalid TCP flag combinations Marcus Meissner (Feb 03)