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TI-2026-25180 Aliases CVE-2026-32688GHSA-q8x4-x7mp-5vg2

Atom table exhaustion via HTTP/2 :scheme pseudo-header in plug_cowboy

Priority MEDIUM 44CWE-770Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-770.

Summary

Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthenticated remote denial of service via atom table exhaustion. Plug.Cowboy.Conn.conn/1 in lib/plug/cowboy/conn.ex calls String.to_atom/1 on the value returned by :cowboy_req.scheme/1. For HTTP/2 connections, cowlib passes the client-supplied :scheme pseudo-header value through verbatim without validation. Each unique value permanently allocates a new entry in the BEAM atom table. Since atoms are never garbage-collected and the atom table has a fixed limit (default 1,048,576), an unauthenticated attacker can exhaust the table by sending HTTP/2 requests with unique :scheme values, causing the Erlang VM to abort with system_limit and taking down the entire node. This vulnerability does not affect HTTP/1.1, where cowboy derives the scheme from the listener type rather than from a client-supplied header. This issue affects plug_cowboy: from 2.0.0 before 2.8.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00545 45th percentileScored 2026-11-07
Fix Fixed plug_cowboy (elixir-plug): 2.8.1plug_cowboy (Hex): 2.8.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
elixir-plugplug_cowboy2.0.0 to before 2.8.12.8.1Patch availableCNA
—plug_cowboy (Hex)2.0.0 to before 2.8.12.8.1Patch availableGHSA-q8x4-x7mp-5vg2
  • plug_cowboy Vendorelixir-plug Affected 2.0.0 to before 2.8.1 Fixed in 2.8.1 Patch available CNA
  • plug_cowboy (Hex) Vendor— Affected 2.0.0 to before 2.8.1 Fixed in 2.8.1 Patch available GHSA-q8x4-x7mp-5vg2

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:elixir-plug:plug.cowboy:*:*:*:*:*:*:*:*2.0.0 to before 2.8.1Vulnerableelixir-plug
  • cpe:2.3:a:elixir-plug:plug.cowboy:*:*:*:*:*:*:*:* Versions 2.0.0 to before 2.8.1 Vulnerable ·elixir-plug

Remediation

  • Fix · CNA plug_cowboy (elixir-plug) Fixed in 2.8.1
  • Fix · GHSA-q8x4-x7mp-5vg2 plug_cowboy (Hex) Fixed in 2.8.1 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-32688
  2. 2026-10-03 Alias added: GHSA-q8x4-x7mp-5vg2
  3. 2026-10-25 EPSS moved to the below the 50th percentile

References

Patch 1

Advisory 4

Other 1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences