CVE-2018-5740

"deny-answer-aliases" is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the security model used by client browsers. However, a defect in this feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Affects BIND 9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4, 9.12.0->9.12.2, 9.13.0->9.13.2.

"deny-answer-aliases" is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the security model used by client browsers. However, a defect in this feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Affects BIND 9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4, 9.12.0->9.12.2, 9.13.0->9.13.2.

"deny-answer-aliases" is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the security model used by client browsers. However, a defect in this feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Affects BIND 9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4, 9.12.0->9.12.2, 9.13.0->9.13.2.

Updated bind packages fix security vulnerability:

In ISC BIND, a defect in thie "deny-answer-aliases" feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Accidental or deliberate triggering of this defect will cause a REQUIRE assertion failure in named, causing the named process to stop execution and resulting in denial of service to clients (CVE-2018-5740).

Note that only servers which have explicitly enabled the "deny-answer-aliases" feature are at risk and disabling the feature prevents exploitation.

This update for bind fixes the following issues:

Security issues fixed:

• CVE-2019-6465: Fixed an issue where controls for zone transfers may not be properly applied to Dynamically Loadable Zones (bsc#1126069).
• CVE-2018-5745: Fixed a denial of service vulnerability if a trust anchor rolls over to an unsupported key algorithm when using managed-keys (bsc#1126068).
• CVE-2018-5743: Fixed a denial of service vulnerability which could be caused by to many simultaneous TCP connections (bsc#1133185).
• CVE-2018-5740: Fixed a denial of service vulnerability in the 'deny-answer-aliases' feature (bsc#1104129).

This update was imported from the SUSE:SLE-15:Update update project.

This update for bind fixes the following issues:

Security issues fixed:

• CVE-2019-6465: Fixed an issue where controls for zone transfers may not be properly applied to Dynamically Loadable Zones (bsc#1126069).
• CVE-2018-5745: Fixed a denial of service vulnerability if a trust anchor rolls over to an unsupported key algorithm when using managed-keys (bsc#1126068).
• CVE-2018-5743: Fixed a denial of service vulnerability which could be caused by to many simultaneous TCP connections (bsc#1133185).
• CVE-2018-5740: Fixed a denial of service vulnerability in the 'deny-answer-aliases' feature (bsc#1104129).

This update for bind fixes the following issues:

Security issues fixed:

• CVE-2018-5740: Fixed a denial of service vulnerability in the 'deny-answer-aliases' feature (bsc#1104129).
• CVE-2018-5743: Limiting simultaneous TCP clients is ineffective. (bsc#1133185)
• CVE-2018-5745: An assertion failure can occur if a trust anchor rolls over to an unsupported key algorithm when using managed-keys. (bsc#1126068)
• CVE-2019-6465: Fixed an issue where controls for zone transfers may not be properly applied to Dynamically Loadable Zones (bsc#1126069).

This update for bind fixes the following issues:

Security issues fixed:

• CVE-2018-5740: Fixed a denial of service vulnerability in the 'deny-answer-aliases' feature (bsc#1104129).
• CVE-2019-6465: Fixed an issue where controls for zone transfers may not be properly applied to Dynamically Loadable Zones (bsc#1126069).
• CVE-2018-5745: An assertion failure can occur if a trust anchor rolls over to an unsupported key algorithm when using managed-keys. (bsc#1126068)
• CVE-2018-5743: Limiting simultaneous TCP clients is ineffective. (bsc#1133185)

This update for bind fixes the following issues:

Security issues fixed:

• CVE-2019-6465: Fixed an issue where controls for zone transfers may not be properly applied to Dynamically Loadable Zones (bsc#1126069).
• CVE-2019-6471: Fixed a reachable assert in dispatch.c. (bsc#1138687)
• CVE-2018-5745: Fixed a denial of service vulnerability if a trust anchor rolls over to an unsupported key algorithm when using managed-keys (bsc#1126068).
• CVE-2018-5743: Fixed a denial of service vulnerability which could be caused by to many simultaneous TCP connections (bsc#1133185).
• CVE-2018-5740: Fixed a denial of service vulnerability in the 'deny-answer-aliases' feature (bsc#1104129).

Non-security issues fixed:

• Don't rely on /etc/insserv.conf anymore for proper dependencies against nss-lookup.target in named.service and lwresd.service (bsc#1118367, bsc#1118368).
• Fix FIPS related regression (bsc#1128220).

It was discovered that Bind incorrectly handled the deny-answer-aliases feature. If this feature is enabled, a remote attacker could use this issue to cause Bind to crash, resulting in a denial of service.