8.2

CVE-2026-47077: Unbounded body accumulation in HTTP/3 response loop in hackney

Analyzed
Published 25-05-2026Last modified 27-05-2026

Vulnerability summary

CVE-2026-47077 is a high (CVSS 8.2) Uncontrolled Resource Consumption vulnerability in benoitc hackney. EPSS estimates a 0.70% chance of exploitation in the next 30 days, higher than 53.3% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Prioritisepublic exploit

Public exploit (GitHub, Date unknown)

Source freshness unavailable

How is this decided?
CVSS score
8.2/10
010
High · v4.0 (CVE.org)
EPSS score
0.70%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Timeline

  1. 25-05-2026
    PublishedVulnerability first disclosed.
  2. 27-05-2026
    Last modifiedVulnerability information updated.

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 metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.70%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.70% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Hackney

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Benoitc1 product
  • hackney≥ 0334af206d5099fdf510ed9eda18e34396f065ad, < 3d25f9fea26c90609de9d64366fedfe5065413bc | ≥ 2.0.0, < 4.0.1

1 vendor · 1 product

References

4 links