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VulnerabilityPublished Updated

CVE-2026-43970: ninenines cowlib · Data Amplification

Affects ninenines cowlibSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High : upgrade to 2.16.1 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 4.0 base score
8.2High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.16.1, 16aad3fb9f81f5cda4d1706ff0c54237c619c282
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade cowlib to 2.16.1; cowlib to 16aad3fb9f81f5cda4d1706ff0c54237c619c282.

Affected software

ProductAffectedFixed in
nineninescowlibAffected
  • >=0.1.0 <2.16.1
Fixed in
  • 2.16.1
nineninescowlibAffected
  • ≥ fad5c0049df278cc498b6cdb519b09e845a070a8, < 16aad3fb9f81f5cda4d1706ff0c54237c619c282
Fixed in
  • 16aad3fb9f81f5cda4d1706ff0c54237c619c282
Hexcowlibpkg:hex/cowlibOther threatsAffected
  • <2.16.1
Fixed in
  • 2.16.1
Hexcowlibpkg:hex/cowlibOther threatsAffected
  • >=0.1.0 <2.16.1
Fixed in
  • 2.16.1

CPE configurations (1)

  • cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, consider implementing network-level protections to block or rate-limit SPDY traffic from untrusted sources. Monitor for unusual memory usage patterns related to SPDY frame processing. Do not rely on generic mitigations unless specifically recommended by the vendor.

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.

References

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