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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.

PUBLISHED Reserved 2026-05-04 | Published 2026-05-13 | Updated 2026-05-15 | Assigner EEF




HIGH: 8.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Product status

Default status
unaffected

0.1.0 (semver) before 2.16.1
affected

Default status
unaffected

fad5c0049df278cc498b6cdb519b09e845a070a8 (git) before 16aad3fb9f81f5cda4d1706ff0c54237c619c282
affected

Credits

Peter Ullrich finder

Loïc Hoguin remediation developer

References

cna.erlef.org/cves/CVE-2026-43970.html related third-party-advisory

osv.dev/vulnerability/EEF-CVE-2026-43970 related

github.com/...ommit/16aad3fb9f81f5cda4d1706ff0c54237c619c282 patch

cve.org (CVE-2026-43970)

nvd.nist.gov (CVE-2026-43970)

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