How severe is GHSA-jq4m-q6p2-8gwc?

No CVSS score has been assigned to GHSA-jq4m-q6p2-8gwc yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-jq4m-q6p2-8gwc?

GHSA-jq4m-q6p2-8gwc affects the following packages: hackney (Hex). Ecosystems affected: Hex.

How do I fix GHSA-jq4m-q6p2-8gwc?

Update hackney to 4.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jq4m-q6p2-8gwc is resolved across your whole dependency graph.

How do I detect GHSA-jq4m-q6p2-8gwc in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackney. 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-jq4m-q6p2-8gwc 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-jq4m-q6p2-8gwc?

O3 pinpoints whether GHSA-jq4m-q6p2-8gwc 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-jq4m-q6p2-8gwc actively exploited in the wild?

No public exploit code has been indexed for GHSA-jq4m-q6p2-8gwc 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.

What type of vulnerability is GHSA-jq4m-q6p2-8gwc?

GHSA-jq4m-q6p2-8gwc is classified as Uncontrolled Resource Consumption (CWE-400). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-jq4m-q6p2-8gwc published, and has it been updated?

GHSA-jq4m-q6p2-8gwc was published on June 26, 2026 and was last updated on June 30, 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

GHSA-jq4m-q6p2-8gwc

Hackney: Per-chunk timeout with unbounded body accumulation enables slow-drip OOM

Also known asCVE-2026-47077EEF-CVE-2026-47077

Published

Jun 26, 2026

Updated

Jun 30, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

💧hackney

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

hackney_h3:await_response_loop/6 in src/hackney_h3.erl accumulates the HTTP/3 response body in memory without any size cap. The after Timeout clause is a per-message inactivity timer, not a wall-clock deadline: every received stream_data chunk, housekeeping select message, or settings frame resets it. A malicious HTTP/3 server that drips one small chunk every Timeout - 1 ms with Fin = false and never terminates the stream keeps the loop alive indefinitely while the accumulation buffer grows without bound, eventually exhausting the BEAM process heap.

Details

In src/hackney_h3.erl, await_response_loop/6 (line 430) builds the body with:

NewBody = <<AccBody/binary, Data/binary>>

There is no max_body check and no monotonic deadline. The after Timeout clause at line 463 is restarted on each loop iteration. A server that ensures at least one message arrives within Timeout ms indefinitely (one small chunk per interval is sufficient) prevents the timeout from firing while AccBody grows linearly. The same module's wait_connected/3 (lines 388-389) shows the correct pattern: track an absolute start time and pass a shrinking Remaining budget into each receive. This loop does not.

Configurations

Only the HTTP/3 transport is affected. Applications using the default TCP/TLS hackney transport are not vulnerable. The vulnerability requires using hackney_h3 directly or passing {transport, h3} to hackney:request/5.

PoC

Stand up an HTTP/3 server that responds with 200 OK headers (Fin = false), then emits a small stream_data chunk every Timeout - margin ms with Fin = false indefinitely.
Issue hackney:request(get, Url, [], <<>>, [{transport, h3}]) against it.
Watch the client process heap grow monotonically. The configured timeout never fires; the process is eventually killed by max_heap_size or the OS OOM killer.

Impact

Remote denial of service via unbounded memory consumption. Affects hackney 2.0.0 through 4.0.0 when using the HTTP/3 transport against an attacker-controlled or attacker-influenced server. Each affected request consumes unbounded memory until the BEAM is killed. CVSS v4.0: 8.2 (HIGH).

Resources

Introduction commit: https://github.com/benoitc/hackney/commit/0334af206d5099fdf510ed9eda18e34396f065ad
Patch commit: https://github.com/benoitc/hackney/commit/3d25f9fea26c90609de9d64366fedfe5065413bc

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`hackney`	≥ 2.0.0&&< 4.0.1	4.0.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hackney. 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 hackney to 4.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jq4m-q6p2-8gwc 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-jq4m-q6p2-8gwc 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-jq4m-q6p2-8gwc. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary `hackney_h3:await_response_loop/6` in `src/hackney_h3.erl` accumulates the HTTP/3 response body in memory without any size cap. The `after Timeout` clause is a per-message inactivity timer, not a wall-clock deadline: every received `stream_data` chunk, housekeeping `select` message, or `settings` frame resets it. A malicious HTTP/3 server that drips one small chunk every `Timeout - 1` ms with `Fin = false` and never terminates the stream keeps the loop alive indefinitely while the accumulation buffer grows without bound, eventually exhausting the BEAM process heap. ### Details I

O3 Security · Impact-Aware SCA

Is GHSA-jq4m-q6p2-8gwc in your dependencies?

O3 detects GHSA-jq4m-q6p2-8gwc 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