{"id":"CVE-2026-69186","summary":"c-ares: Memory-amplification denial of service via unvalidated DNS header record counts","details":"c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 1.34.7.","aliases":["GHSA-jv8r-gqr9-68wj"],"modified":"2026-09-20T08:19:49.925079Z","published":"2026-09-18T17:25:42.440Z","related":["SUSE-SU-2026:23364-1","SUSE-SU-2026:23414-1","SUSE-SU-2026:4021-1","openSUSE-SU-2026:11593-1","openSUSE-SU-2026:21721-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69186.json"},"references":[{"type":"WEB","url":"https://github.com/c-ares/c-ares/releases/tag/v1.34.7"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69186.json"},{"type":"ADVISORY","url":"https://github.com/c-ares/c-ares/security/advisories/GHSA-jv8r-gqr9-68wj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-69186"},{"type":"FIX","url":"https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4"},{"type":"FIX","url":"https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"},{"type":"FIX","url":"https://github.com/c-ares/c-ares/pull/1134"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/c-ares/c-ares","events":[{"introduced":"0"},{"fixed":"e47c203f91cd8b749c8736bc18d75a31ffdec8f4"},{"fixed":"eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"},{"fixed":"d63b7de3a3568d14ab1351374b205365aed51cca"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"1.34.7"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v1.34.6","v1.34.5","v1.34.4","v1.34.3","v1.34.2","v1.34.1","v1.34.0","v1.31.0","cares-1_29_0","cares-1_28_1","cares-1_28_0","cares-1_27_0","cares-1_26_0","cares-1_25_0","cares-1_24_0","cares-1_23_0","cares-1_22_1","cares-1_22_0","cares-1_21_0","cares-1_20_1","cares-1_20_0","cares-1_19_1","cares-1_19_0","cares-1_18_1","cares-1_18_0","cares-1_17_2","cares-1_17_1","c-ares-1_17_0","cares-1_16_1","cares-1_16_0","cares-1_15_0","cares-1_14_0","cares-1_13_0","cares-1_12_0","cares-1_11_0","cares-1_11_0-rc1","cares-1_10_0","cares-1_9_1","cares-1_9_0","cares-1_8_0","cares-1_7_5","cares-1_7_4","cares-1_7_3","cares-1_7_2","cares-1_7_1","curl-7_20_0","cares-1_7_0","curl-7_19_7","curl-7_19_6","curl-7_19_5","curl-7_19_4","curl-7_19_3","cares-1_6_0","curl-7_19_2","curl-7_19_0","cares-1_5_3","curl-7_18_2","cares-1_5_2","curl-7_18_1","curl-7_18_0","cares-1_5_1","cares-1_5_0","curl-7_17_1","curl-7_17_0","curl-7_16_4","curl-7_16_3","cares-1_4_0","curl-7_16_2","curl-7_16_1","cares-1_3_2","curl-7_16_0","curl-7_15_6-prepipeline","curl-7_15_5","cares-1_3_1","curl-7_15_4","curl-7_15_3","curl-7_15_1","curl-7_15_0","curl-7_14_1","curl-7_14_0","curl-7_13_2","curl-7_13_1","curl-7_13_0","cares-1_2_1","curl-7_12_2","curl-7_12_1","curl-7_12_0","c-ares-1_2_0","curl-7_11_1","cares-1_1_0","curl-7_11_0","curl-7_10_8"],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-69186.json","vanir_signatures_modified":"2026-09-20T08:19:49Z","vanir_signatures":[{"signature_type":"Function","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab","target":{"function":"ares_dns_parse_header","file":"src/lib/record/ares_dns_parse.c"},"deprecated":false,"digest":{"function_hash":"339369170279688869394972447116353873681","length":1975},"id":"CVE-2026-69186-03106c5a"},{"digest":{"line_hashes":["269745032999509763615118565117448913611","293850083987775466205461459497353455979","323010113770663544280306504698269929440","30681434477766079920299812049078742637","38929257534299927680856913954246546348","15895386558806833721634587351085961895","124583247596904972311902091601606185919","59145353781277769958429907150297724971","185964326092560203476263515832635856067","5163151457131041087841222716786088906","226803838471376103552112412834119684715","95349107419783900172797516646485645226","316101072733228499413168884574648477245","124583247596904972311902091601606185919","208406617252468407765357363806351664847","214868768765460906184885095253828154881","197199470108670351154919151783174798803","266151619187248766745223437364952829851","323630750925285021174066480995849323975","293112365652976552277499496391485830546","124583247596904972311902091601606185919","72688991973933606185779345763108035723","303764570121988436663674128373546599905","254719075592665960425533569434171579843","3691270663326971301145206482899743434","289174478929386660407025304800871917030","317829815559797888745331349974067007101","192093125591080348095403894980793635153","146547429792180302822249306634742035247","991938742186947232412904668194235179","219054902886563942771950554648557493340"],"threshold":0.9},"id":"CVE-2026-69186-9c5f528d","signature_type":"Line","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4","target":{"file":"src/lib/record/ares_dns_parse.c"},"deprecated":false},{"digest":{"line_hashes":["292947636881127679123105674089199271794","161213211813900988351898049535261271704"],"threshold":0.9},"id":"CVE-2026-69186-a0b6b35f","signature_type":"Line","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab","target":{"file":"test/ares-test-parse.cc"},"deprecated":false},{"deprecated":false,"digest":{"function_hash":"229522228889724405761407632642095855034","length":1381},"id":"CVE-2026-69186-b97ab270","signature_type":"Function","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4","target":{"file":"src/lib/record/ares_dns_parse.c","function":"ares_dns_parse_buf"}},{"signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4","target":{"file":"test/ares-test-parse.cc"},"deprecated":false,"digest":{"line_hashes":["292947636881127679123105674089199271794","161213211813900988351898049535261271704"],"threshold":0.9},"id":"CVE-2026-69186-ca503a7d","signature_type":"Line"},{"target":{"file":"src/lib/record/ares_dns_parse.c"},"deprecated":false,"digest":{"line_hashes":["269745032999509763615118565117448913611","293850083987775466205461459497353455979","323010113770663544280306504698269929440","30681434477766079920299812049078742637","38929257534299927680856913954246546348","15895386558806833721634587351085961895","124583247596904972311902091601606185919","59145353781277769958429907150297724971","185964326092560203476263515832635856067","5163151457131041087841222716786088906","226803838471376103552112412834119684715","95349107419783900172797516646485645226","316101072733228499413168884574648477245","124583247596904972311902091601606185919","208406617252468407765357363806351664847","214868768765460906184885095253828154881","197199470108670351154919151783174798803","266151619187248766745223437364952829851","323630750925285021174066480995849323975","293112365652976552277499496391485830546","124583247596904972311902091601606185919","72688991973933606185779345763108035723","303764570121988436663674128373546599905","254719075592665960425533569434171579843","3691270663326971301145206482899743434","289174478929386660407025304800871917030","317829815559797888745331349974067007101","192093125591080348095403894980793635153","146547429792180302822249306634742035247","991938742186947232412904668194235179","219054902886563942771950554648557493340"],"threshold":0.9},"id":"CVE-2026-69186-cc27f06f","signature_type":"Line","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"},{"target":{"file":"src/lib/record/ares_dns_parse.c","function":"ares_dns_parse_buf"},"deprecated":false,"digest":{"length":1381,"function_hash":"229522228889724405761407632642095855034"},"id":"CVE-2026-69186-d9585494","signature_type":"Function","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/eaded4cb200b2a5f8d73f11021ff7c8d6968aaab"},{"deprecated":false,"digest":{"function_hash":"339369170279688869394972447116353873681","length":1975},"id":"CVE-2026-69186-e3303cda","signature_type":"Function","signature_version":"v1","source":"https://github.com/c-ares/c-ares/commit/e47c203f91cd8b749c8736bc18d75a31ffdec8f4","target":{"function":"ares_dns_parse_header","file":"src/lib/record/ares_dns_parse.c"}}]}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}