CVE-2026-47077

Description

Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. hackney_h3:await_response_loop/6 accumulates the HTTP/3 response body in memory without any size cap. The after Timeout clause is a per-message inactivity timer that resets on every received chunk, housekeeping message, or settings frame — it is not a wall-clock deadline. A malicious HTTP/3 server that emits one small chunk every Timeout - 1 ms with Fin = false and never sends a final frame keeps the loop alive indefinitely while the accumulation buffer grows linearly without bound, eventually exhausting the BEAM process heap and causing an out-of-memory condition. This issue affects hackney: from 2.0.0 before 4.0.1.

CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.13%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

Affected Products

Vendor	Product	Versions
benoitc	hackney	2.0.0 — 4.0.1

References

Advisories & Patches

https://cna.erlef.org/cves/CVE-2026-47077.html https://github.com/benoitc/hackney/commit/3d25f9fea26c90609de9d64366fedfe5065413bc https://github.com/benoitc/hackney/security/advisories/GHSA-jq4m-q6p2-8gwc https://osv.dev/vulnerability/EEF-CVE-2026-47077 https://github.com/benoitc/hackney/security/advisories/GHSA-jq4m-q6p2-8gwc

Exploits

https://github.com/benoitc/hackney/security/advisories/GHSA-jq4m-q6p2-8gwc https://github.com/benoitc/hackney/security/advisories/GHSA-jq4m-q6p2-8gwc

Frequently Asked Questions

What is CVE-2026-47077? +

Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. hackney_h3:await_response_loop/6 accumulates the HTTP/3 response body in memory without any size cap. The after Timeout clause is a per-message inactivity timer that resets on every received chunk, housekeeping message, or settings frame — it is not a wall-clock deadline. A malicious HTTP/3 server that emits one small chunk every Timeout - 1 ms with Fin = false and never sends a final frame keeps the loop alive indefinitely while the accumulation buffer grows linearly without bound, eventually exhausting the BEAM process heap and causing an out-of-memory condition. This issue affects hackney: from 2.0.0 before 4.0.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-47077? +

CVE-2026-47077 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-47077? +

CVE-2026-47077 affects products from benoitc, specifically: hackney. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-47077? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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