How severe is GHSA-q8x4-x7mp-5vg2?

No CVSS score has been assigned to GHSA-q8x4-x7mp-5vg2 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-q8x4-x7mp-5vg2?

GHSA-q8x4-x7mp-5vg2 affects the following packages: plug_cowboy (Hex). Ecosystems affected: Hex.

How do I fix GHSA-q8x4-x7mp-5vg2?

Update plug_cowboy to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q8x4-x7mp-5vg2 is resolved across your whole dependency graph.

How do I detect GHSA-q8x4-x7mp-5vg2 in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plug_cowboy. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-q8x4-x7mp-5vg2 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-q8x4-x7mp-5vg2?

O3 pinpoints whether GHSA-q8x4-x7mp-5vg2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-q8x4-x7mp-5vg2 actively exploited in the wild?

No public exploit code has been indexed for GHSA-q8x4-x7mp-5vg2 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-q8x4-x7mp-5vg2 published, and has it been updated?

GHSA-q8x4-x7mp-5vg2 was published on May 5, 2026 and was last updated on May 5, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💧 Hex

Not in CISA KEV

GHSA-q8x4-x7mp-5vg2

Fix: elixir-plug/plug_cowboy@bfb34cb

GHSA-q8x4-x7mp-5vg2 is a security vulnerability in plug_cowboy. O3 Security confirms whether GHSA-q8x4-x7mp-5vg2 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Plug.Cowboy vulnerable to unauthenticated remote DoS via HTTP/2 `:scheme` atom-table exhaustion

Also known asCVE-2026-32688EEF-CVE-2026-32688

Published

May 5, 2026

Updated

May 5, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of May 5, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

💧plug_cowboy

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.

Description

Summary

An unauthenticated remote denial-of-service vulnerability in Plug.Cowboy.Conn allows any attacker who can reach an HTTPS Plug.Cowboy listener via HTTP/2 to permanently exhaust the BEAM atom table and crash the entire Erlang VM.

Am I Affected?

All users running plug_cowboy with HTTP/2 may be affected, this includes Phoenix applications. If another HTTP adapter such as Bandit is used, then the consuming project is not affected. If the HTTP/2 endpoint is exposed directly (without a proxy) then the project will be affected. If a proxy is in use then it depends on the proxy configuration. Many proxies use HTTP/1.1 internally, and would be unaffected.

Impact

The vulnerability will allow crashing the Erlang VM (BEAM) via atom exhaustion.

Mitigation

Users are advised to update to plug_cowboy v2.8.1 to mitigate this issue.

Credits

Plug.Cowboy thanks Peter Ullrich for finding and responsibly disclosing this vulnerability.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`plug_cowboy`	≥ 2.0.0&&< 2.8.1	2.8.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plug_cowboy. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update plug_cowboy to 2.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q8x4-x7mp-5vg2 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-q8x4-x7mp-5vg2 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-q8x4-x7mp-5vg2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary An unauthenticated remote denial-of-service vulnerability in `Plug.Cowboy.Conn` allows any attacker who can reach an HTTPS Plug.Cowboy listener via HTTP/2 to permanently exhaust the BEAM atom table and crash the entire Erlang VM. ## Am I Affected? All users running plug_cowboy with HTTP/2 may be affected, this includes Phoenix applications. If another HTTP adapter such as Bandit is used, then the consuming project is not affected. If the HTTP/2 endpoint is exposed directly (without a proxy) then the project will be affected. If a proxy is in use then it depends on the proxy confi

O3 Security · Impact-Aware SCA

Is GHSA-q8x4-x7mp-5vg2 in your dependencies?

O3 detects GHSA-q8x4-x7mp-5vg2 across Hex dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works