CVE-2020-22217

Buffer overflow vulnerability in c-ares before 1_16_1 thru 1_17_0 via function ares_parse_soa_reply in ares_parse_soa_reply.c.

Buffer overflow vulnerability in c-ares before 1_16_1 thru 1_17_0 via function ares_parse_soa_reply in ares_parse_soa_reply.c.

The c-ares C library defines asynchronous DNS (Domain Name System) requests and provides name resolving API.

Security Fix(es):

• c-ares: Heap buffer over read in ares_parse_soa_reply (CVE-2020-22217)
• c-ares: Buffer Underwrite in ares_inet_net_pton() (CVE-2023-31130)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The c-ares C library defines asynchronous DNS (Domain Name System) requests and provides name resolving API.

Security Fix(es):

• c-ares: Heap buffer over read in ares_parse_soa_reply (CVE-2020-22217)

• c-ares: Buffer Underwrite in ares_inet_net_pton() (CVE-2023-31130)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

This update for libcares2 fixes the following issues:

• CVE-2020-22217: Fixed an out of bounds read in ares_parse_soa_reply(). (bsc#1214674)

It was discovered that c-ares incorrectly parsed certain SOA replies. A remote attacker could possibly use this issue to cause c-res to crash, resulting in a denial of service.

It was discovered that c-ares incorrectly parsed certain SOA replies. A remote attacker could possibly use this issue to cause c-ares to crash, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS and Ubuntu 18.04 LTS. (CVE-2020-22217)

It was discovered that c-ares incorrectly handled certain sortlist strings. A remote attacker could possibly use this issue to cause c-ares to crash, resulting in a denial of service, or execute arbitrary code. This issue only affected Ubuntu 16.04 LTS. (CVE-2022-4904)

It was discovered that c-ares did not properly limit DNS compression pointer hops or assembled name lengths when parsing DNS names. A remote attacker could possibly use this issue to cause c-ares to use excessive resources, resulting in a denial of service. (CVE-2026-69184)

It was discovered that c-ares did not properly validate record count fields before allocating memory when parsing DNS responses. A remote attacker could possibly use this issue to cause c-ares to use excessive resources, resulting in a denial of service. This issue only affected Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-69186)