CVE-2026-32688: Allocation of Resources Without Limits or Throttling vulnerability in elixir-plug plug_cowboy allows unauthent

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HIGH 7.5REMOTEUPGRADE

CVE-2026-32688 is a high-severity flaw (CVSS 7.5) affecting plug.cowboy. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 alloca

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-04-27
Last modified	2026-10-26

Publisher (CNA): EEF · Vendor: elixir-plug

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-27 14:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

elixir-plug plug.cowboy UPGRADE

Affected: >= 2.0.0 and < 2.8.1

Fixed in: 2.8.1

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy plug.cowboy || rpm -q plug.cowboy || plug.cowboy --version

2. UPGRADE to 2.8.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade plug.cowboy

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade plug.cowboy

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison plug.cowboy sudo apt install plug.cowboy=<VERSION_BEFORE_2.0.0> sudo apt-mark hold plug.cowboy

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list plug.cowboy sudo dnf downgrade plug.cowboy-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add plug.cowboy

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-32688?

plug.cowboy: upgrade to 2.8.1. Exact commands for each OS are on this page.

Is CVE-2026-32688 being exploited?

CVE-2026-32688 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-32688 affect?

CVE-2026-32688 affects plug.cowboy. Severity is high (CVSS 7.5). 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_ato

How urgent is CVE-2026-32688?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

References

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