{"id":"CVE-2026-43970","state":"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.","publishedAt":"2026-05-13T18:43:11.640Z","updatedAt":"2026-05-15T04:33:30.898Z","severity":{"score":8.2,"label":"High","version":"4.0","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","source":"EEF"},"assigner":"EEF","products":["ninenines cowlib"],"affected":[{"vendor":"ninenines","product":"cowlib","packageName":"cowlib","packageURL":"pkg:hex/cowlib","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"2.16.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"],"modules":["cow_spdy"],"programFiles":["src/cow_spdy.erl"],"programRoutines":[{"name":"cow_spdy:parse/2"},{"name":"cow_spdy:inflate/2"},{"name":"cow_spdy:parse_headers/2"},{"name":"cow_spdy:parse_headers/4"}],"repo":"https://github.com/ninenines/cowlib"},{"vendor":"ninenines","product":"cowlib","packageName":"ninenines/cowlib","packageURL":"pkg:github/ninenines/cowlib","defaultStatus":"unaffected","versions":[{"version":"fad5c0049df278cc498b6cdb519b09e845a070a8","status":"affected","lessThan":"16aad3fb9f81f5cda4d1706ff0c54237c619c282","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"],"modules":["cow_spdy"],"programFiles":["src/cow_spdy.erl"],"programRoutines":[{"name":"cow_spdy:parse/2"},{"name":"cow_spdy:inflate/2"},{"name":"cow_spdy:parse_headers/2"},{"name":"cow_spdy:parse_headers/4"}],"repo":"https://github.com/ninenines/cowlib"}],"references":["https://cna.erlef.org/cves/CVE-2026-43970.html","https://osv.dev/vulnerability/EEF-CVE-2026-43970","https://github.com/ninenines/cowlib/commit/16aad3fb9f81f5cda4d1706ff0c54237c619c282"],"weaknesses":["CWE-409"],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43970.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43970","state":"PUBLISHED","datePublished":"2026-05-13T18:43:11.640Z","dateUpdated":"2026-05-15T04:33:30.898Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-05-04T18:23:25.574Z"},"containers":{"cna":{"title":"Decompression Bomb in cow_spdy:inflate/2 Allows Memory Exhaustion via Crafted SPDY Frame","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"ninenines","product":"cowlib","packageName":"cowlib","packageURL":"pkg:hex/cowlib","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"2.16.1","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"],"modules":["cow_spdy"],"programFiles":["src/cow_spdy.erl"],"programRoutines":[{"name":"cow_spdy:parse/2"},{"name":"cow_spdy:inflate/2"},{"name":"cow_spdy:parse_headers/2"},{"name":"cow_spdy:parse_headers/4"}],"repo":"https://github.com/ninenines/cowlib"},{"vendor":"ninenines","product":"cowlib","packageName":"ninenines/cowlib","packageURL":"pkg:github/ninenines/cowlib","defaultStatus":"unaffected","versions":[{"version":"fad5c0049df278cc498b6cdb519b09e845a070a8","status":"affected","lessThan":"16aad3fb9f81f5cda4d1706ff0c54237c619c282","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*"],"modules":["cow_spdy"],"programFiles":["src/cow_spdy.erl"],"programRoutines":[{"name":"cow_spdy:parse/2"},{"name":"cow_spdy:inflate/2"},{"name":"cow_spdy:parse_headers/2"},{"name":"cow_spdy:parse_headers/4"}],"repo":"https://github.com/ninenines/cowlib"}],"references":[{"url":"https://cna.erlef.org/cves/CVE-2026-43970.html","tags":["related","third-party-advisory"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-43970","tags":["related"]},{"url":"https://github.com/ninenines/cowlib/commit/16aad3fb9f81f5cda4d1706ff0c54237c619c282","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":8.2,"baseSeverity":"HIGH","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-409","description":"CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-05-15T04:33:30.898Z"},"configurations":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>The application must use <tt>cow_spdy:parse/2</tt> to parse SPDY frames from an untrusted peer. cowboy itself does not use <tt>cow_spdy</tt>; only direct callers of the <tt>cow_spdy</tt> API are affected.</p>"}],"value":"The 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."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*","versionEndExcluding":"2.16.1","versionStartIncluding":"0.1.0","vulnerable":true}],"negate":false,"operator":"OR"}]}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Loïc Hoguin"}],"impacts":[{"capecId":"CAPEC-130","descriptions":[{"lang":"en","value":"CAPEC-130 Excessive Allocation"}]}],"solutions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"<p>Upgrade to cowlib 2.16.1 or later, in which the <tt>cow_spdy</tt> module has been removed entirely. No patched version of <tt>cow_spdy</tt> will be provided. Migrate away from SPDY, which has been deprecated since 2015 in favour of HTTP/2.</p>"}],"value":"Upgrade 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."}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-05-14T12:38:59.086048Z","id":"CVE-2026-43970","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-05-14T12:39:10.669Z"}}]}}}