{"id":"CVE-2026-43970","aliases":["DEBIAN-CVE-2026-43970","EEF-CVE-2026-43970","EUVD-2026-30131","GHSA-84f2-rp86-235p","UBUNTU-CVE-2026-43970"],"status":"published","title":"Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","severity":{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00511,"percentile":0.43902,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-409"],"published":"2026-05-13T18:43:11Z","modified":"2026-11-11T02:48:58Z","fixes":[{"ecosystem":"Hex","package":"cowlib","fixed_in":["2.16.1"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:14","package":"erlang-cowlib","fixed_in":["2.17.1-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"fixed":"2.16.1"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3","2.17.1-1","2.17.1-2","2.18.0-1","2.19.0-1","2.20.0-1","2.21.0-1"]},{"source":"osv","ecosystem":"Debian:13","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3","2.17.1-1","2.17.1-2","2.18.0-1","2.19.0-1","2.20.0-1","2.21.0-1"]},{"source":"osv","ecosystem":"Debian:14","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.17.1-1"}]}],"versions":["1.3.0-3"]},{"source":"osv","ecosystem":"Hex","package":"cowlib","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"2.16.1"}]}],"versions":["1.0.0","1.0.1","1.0.2","1.1.0","1.2.0","1.3.0","2.0.0","2.0.1","2.1.0","2.10.0","2.10.1","2.11.0","2.12.0","2.12.1","2.13.0","2.14.0","2.15.0","2.16.0","2.2.0","2.2.1","2.3.0","2.4.0","2.5.0","2.5.1","2.6.0","2.7.0","2.7.1","2.7.2","2.7.3","2.8.0","2.9.0","2.9.1"]},{"source":"osv","ecosystem":"Hex","package":"cowlib","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"2.16.1"}]}],"versions":["1.0.0","1.0.1","1.0.2","1.1.0","1.2.0","1.3.0","2.0.0","2.0.1","2.1.0","2.10.0","2.10.1","2.11.0","2.12.0","2.12.1","2.13.0","2.14.0","2.15.0","2.16.0","2.2.0","2.2.1","2.3.0","2.4.0","2.5.0","2.5.1","2.6.0","2.7.0","2.7.1","2.7.2","2.7.3","2.8.0","2.9.0","2.9.1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-1"]},{"source":"osv","ecosystem":"Ubuntu:18.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-2"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3build1","2.19.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"erlang-cowlib","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.0-3","1.3.0-3build1"]}],"products":[{"vendor":"ninenines","product":"cowlib"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-43970.html","tags":["related","third-party-advisory","advisory","web","report"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-43970","tags":["related","web","report"]},{"url":"https://github.com/ninenines/cowlib/commit/16aad3fb9f81f5cda4d1706ff0c54237c619c282","tags":["patch","fix","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-43970","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-84f2-rp86-235p"},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43970.json","tags":["advisory"]},{"url":"https://github.com/ninenines/cowlib","tags":["package"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-43970","tags":["advisory"]},{"url":"https://hex.pm/packages/cowlib","tags":["package"]},{"url":"https://ubuntu.com/security/CVE-2026-43970","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-43970","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-43970","title":"Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T18:43:11.64Z","modified":"2026-05-15T04:33:30.898Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T13:37:36.275898Z"}],"euvd":[{"id":"EUVD-2026-30131","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T18:43:11Z","modified":"2026-05-15T04:33:30Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T19:04:30.03108Z"}],"ghsa":[{"id":"GHSA-84f2-rp86-235p","title":"cowlib: Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T21:32:06Z","modified":"2026-05-19T20:12:02Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:40:12.430932Z"}],"nvd":[{"id":"CVE-2026-43970","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T19:17:25.44Z","modified":"2026-10-26T17:10:03.27Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:12:19.020465Z"}],"osv":[{"id":"CVE-2026-43970","title":"Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T18:43:11.64Z","modified":"2026-11-11T02:48:58.800411368Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-11T03:21:32.226287Z"},{"id":"DEBIAN-CVE-2026-43970","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.  cow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.  This issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T19:17:25.44Z","modified":"2026-10-27T10:01:40.726141003Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"}],"updated_at":"2026-11-02T15:45:55.669088Z"},{"id":"EEF-CVE-2026-43970","title":"Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"## Summary\n\nImproper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow\\_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn\\_stream, syn\\_reply, and headers frame types are all affected via cow\\_spdy:parse\\_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.\n\n## Configurations\n\nThe application must use cow\\_spdy:parse/2 to parse SPDY frames from an untrusted peer. cowboy itself does not use cow\\_spdy; only direct callers of the cow\\_spdy API are affected.\n\n## Solutions\n\nUpgrade to cowlib 2.16.1 or later, in which the cow\\_spdy module has been removed entirely. No patched version of cow\\_spdy will be provided. Migrate away from SPDY, which has been deprecated since 2015 in favour of HTTP/2.","status":"published","published":"2026-05-13T18:43:11.64Z","modified":"2026-09-08T03:45:06.180638182Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:46:33.047032Z"},{"id":"GHSA-84f2-rp86-235p","title":"cowlib: Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion.\n\ncow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2.\n\nThis issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T21:32:06Z","modified":"2026-05-19T20:26:01.036608498Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:46:41.732368Z"},{"id":"UBUNTU-CVE-2026-43970","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in ninenines cowlib allows unauthenticated remote denial of service via memory exhaustion. cow_spdy:inflate/2 in cowlib passes peer-supplied compressed bytes directly to zlib:inflate/2 with no output size bound. The SPDY header compression dictionary (?ZDICT) is public, and zlib compresses long runs of repeated bytes at roughly 1024:1, so a few kilobytes of SPDY frame payload can decompress to gigabytes on the BEAM heap, OOM-killing the node. A single unauthenticated SPDY frame is sufficient to trigger the condition. The parsers for syn_stream, syn_reply, and headers frame types are all affected via cow_spdy:parse_headers/2. This issue affects cowlib from 0.1.0 before 2.16.1.","status":"published","published":"2026-05-13T19:17:00Z","modified":"2026-10-17T12:58:18.425648556Z","cvss":[{"version":"4.0","score":8.2,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T16:56:22.075798Z"}]}}