CVE-2026-43970

UNSCORED

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.

CWE-409

How to fix

Remediation Available

erlang-cowlibDebian

Fixed in:2.17.1-1CVE-2026-43970

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3.1 Vector

No CVSS vector data available.

Exploit Intelligence

0.51%probability of exploitation in 30 days

41stpercentile

Moderate risk: more likely to be exploited than 41% of all known CVEs.

References

Other references3

Related Vulnerabilities

Other CWE-409 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2026-49975	High	7.5	28%	-	Fix
CVE-2026-21441	High	7.5	2.7%	-	Fix
CVE-2024-43499	High	7.5	2.6%	-	Fix
CVE-2024-28180	Medium	4.3	2.0%	-	Fix
CVE-2017-16129	Medium	5.9	1.8%	-	Fix
CVE-2022-29225	High	7.5	1.5%	-	Fix

Common questions

How do I fix CVE-2026-43970?

Upgrade erlang-cowlib on debian unstable to 2.17.1-1 or later.

Is CVE-2026-43970 being actively exploited?

Not that we know of. CVE-2026-43970 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.51% is the estimated probability that it will be exploited in the next 30 days. That is higher than 41% of all scored CVEs.

What does CVE-2026-43970 affect?

Published advisories record a fix for erlang-cowlib (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-14.