🛡️ CVE-2026-43970 on Debian — erlang-cowlib

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-43970 as tracked by Debian, for the package erlang-cowlib. The fix is available in version 2.17.1-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

DEBIAN-CVE-2026-43970 is classified as CWE-409: Improper Handling of Highly Compressed Data (Data Amplification). The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

Affected software

DEBIAN-CVE-2026-43970 is recorded against 1 package.

  • erlang-cowlib (fixed in 2.17.1-1)

Timeline and source

Published on 13 May 2026 and last revised on 4 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2026-43970 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-05-13
Updated 2026-08-20
Modified 2026-08-04
Fix URL N/A

Affected Packages

Software From version Fixed in
erlang-cowlib — 2.17.1-1

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