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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| ninenines | cowlib | 0.1.0 – < 2.16.1 | 2.16.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | erlang-cowlib | 2.17.1-1 | — |
| Debian 13 | erlang-cowlib | No fix yet | — |
| Debian 12 | erlang-cowlib | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | erlang-cowlib | No fix yet | — |
| Ubuntu 26.04 LTS | erlang-cowlib | No fix yet | — |
| Ubuntu 25.10 | erlang-cowlib | No fix yet | — |
| Ubuntu 24.04 LTS | erlang-cowlib | No fix yet | — |
| Ubuntu 22.04 LTS | erlang-cowlib | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | erlang-cowlib | No fix yet | — |
| Ubuntu 18.04 LTS | erlang-cowlib | No fix yet | — |
| Ubuntu 16.04 LTS | erlang-cowlib | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Hex | cowlib | >= 0.1.0, < 2.16.1 | 2.16.1 | EEF-CVE-2026-43970 |
References
- https://cna.erlef.org/cves/CVE-2026-43970.html related third-party-advisory
- https://osv.dev/vulnerability/EEF-CVE-2026-43970 related
- https://github.com/ninenines/cowlib/commit/16aad3fb9f81f5cda4d1706ff0c54237c619c282 patch