CVE-2012-2663
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Description
The CVE Program describes this issue as:
extensions/libxt_tcp.c in iptables through 1.4.21 does not match TCP SYN+FIN packets in --syn rules, which might allow remote attackers to bypass intended firewall restrictions via crafted packets. NOTE: the CVE-2012-6638 fix makes this issue less relevant.
Statement
This issue does affect Red Hat Enterprise Linux 5 and 6.
The risks in breaking compatability associated with fixing this flaw outweigh the benefits of the fix, therefore Red Hat does not plan to fix this flaw in Red Hat Enterprise Linux 5 and 6.
Please note that the remote DoS issue in the way how Linux kernel treats SYN+FIN flags set is being handled under different CVE, CVE-2012-6638, and is planned to be fixed in all affected Red Hat Enterprise Linux releases.
Mitigation
Instead of --syn use --tcp-flags SYN,RST,ACK SYN in your rulesets in case you want to also match packets with both SYN+FIN flags set.
Additional information
- Bugzilla 826702: iptables: --syn flag bypass
- FAQ: Frequently asked questions about CVE-2012-2663
Common Vulnerability Scoring System (CVSS) Score Details
Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
| Red Hat | NVD | |
|---|---|---|
CVSS v2 Base Score | 6.4 | 7.5 |
Attack Vector | Network | Network |
Access Complexity | Low | Low |
Authentication | None | None |
Confidentiality Impact | Partial | Partial |
Integrity Impact | None | Partial |
Availability Impact | Partial | Partial |
CVSS v2 Vector
Red Hat: AV:N/AC:L/Au:N/C:P/I:N/A:P
NVD: AV:N/AC:L/Au:N/C:P/I:P/A:P
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
What can I do if my product is listed as "Will not fix"?
What can I do if my product is listed as "Fix deferred"?
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
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