CVE-2026-56811: Allocation of Resources Without Limits or Throttling vulnerability in phoenixframework phoenix (Phoenix.Socket

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HIGH 7.5REMOTEUPGRADE

CVE-2026-56811 is a high-severity flaw (CVSS 7.5) affecting phoenix. 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 phoenixframework phoenix (Phoenix.Socket module) allows an unauthenticated attacker to cause a denial of service against any endpoint that mounts a Phoenix socket with a reachable channel transport (WebSocket or LongPoll). This vulnerability is associated with program files lib/phoenix/socket.ex and program routine 'Elixir.Phoenix.Socket':handle_in/4. Phoenix transports do no

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	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-07-07
Last modified	2026-10-25

Publisher (CNA): EEF · Vendor: phoenixframework

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-07 16:16 UTCPublished CVE record published
2026-10-25 20:10 UTCUpdated Record last modified

phoenixframework phoenix UPGRADE

Affected: >= 1.2.0 and < 1.5.15 · >= 1.6.0 and < 1.6.17 · >= 1.7.0 and < 1.7.24 · >= 1.8.0 and < 1.8.9

Fixed in: 1.5.15, 1.6.17, 1.7.24, 1.8.9

Safe to downgrade to: a release before 1.2.0

1. Check installed version

apt-cache policy phoenix || rpm -q phoenix || phoenix --version

2. UPGRADE to 1.5.15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade phoenix

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade phoenix

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 1.2.0 (Debian / Ubuntu)

apt-cache madison phoenix sudo apt install phoenix=<VERSION_BEFORE_1.2.0> sudo apt-mark hold phoenix

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

dnf --showduplicates list phoenix sudo dnf downgrade phoenix-<VERSION_BEFORE_1.2.0> sudo dnf versionlock add phoenix

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-2026-56811?

phoenix: upgrade to 1.5.15, 1.6.17, 1.7.24, 1.8.9. Exact commands for each OS are on this page.

Is CVE-2026-56811 being exploited?

CVE-2026-56811 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-2026-56811 affect?

CVE-2026-56811 affects phoenix. Severity is high (CVSS 7.5). Allocation of Resources Without Limits or Throttling vulnerability in phoenixframework phoenix (Phoenix.Socket module) allows an unauthenticated attacker to cause a denial of service against any endpoint that mounts a Phoenix socket with a

How urgent is CVE-2026-56811?

Priority 45/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-56812 HIGH 7.5 UPGRADE Improper Check for Unusual or Exceptional Conditions vulnerability in phoenixframework phoenix (Presence JavaS

References

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