The DNS stub resolver in the GNU C Library (aka glibc or libc6) before version 2.26, when EDNS support is enabled, will solicit large UDP responses from name servers, potentially simplifying off-path DNS spoofing attacks due to IP fragmentation.
The MITRE CVE dictionary describes this issue as:
Find out more about CVE-2017-12132 from the MITRE CVE dictionary dictionary and NIST NVD.
This issue only affects systems which use a remote recursive resolver and enable EDNS0, either with the “edns0” option in /etc/resolv.conf, or using the RES_USE_EDNS0 or RES_USE_DNSSEC resolver flags. The underlying issue affects recursive resolvers such as BIND and Unbound as well, and has to be fixed separately there.
| CVSS3 Base Score | 3 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:L/A:N |
| Attack Vector | Network |
| Attack Complexity | High |
| Privileges Required | Low |
| User Interaction | Required |
| Scope | Changed |
| Confidentiality | None |
| Integrity Impact | Low |
| Availability Impact | None |
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat Enterprise Linux 7 (glibc) | RHSA-2018:0805 | 2018-04-10 |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 7 | compat-glibc | Will not fix |
| Red Hat Enterprise Linux 6 | compat-glibc | Will not fix |
| Red Hat Enterprise Linux 6 | glibc | Will not fix |
| Red Hat Enterprise Linux 5 | compat-glibc | Will not fix |
| Red Hat Enterprise Linux 5 | glibc | Will not fix |
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