CVE-2026-47067: Atom table exhaustion via unrecognized URL schemes in hackney
Noroxi assessment
Priority: Monitor (action score 34/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.75% (FIRST EPSS); higher than 55.3% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: benoitc hackney 31f6f0e27e096ad88743dfded4f030a3ee74972e, 4.0.1.
Low priority for now. Upgrade to benoitc hackney 31f6f0e27e096ad88743dfded4f030a3ee74972e, 4.0.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The URL parser in src/hackney_url.erl converts every unrecognized URL scheme to a permanent BEAM atom via binary_to_atom/2. BEAM atoms are never garbage-collected and the atom table defaults to a hard limit of 1,048,576 entries. An attacker who can supply URLs with attacker-chosen scheme prefixes — directly as request targets, as configured webhook URLs, or via Location headers followed during redirects — can exhaust the atom table and crash the entire BEAM VM with system_limit. This issue affects hackney: from 2.0.0 before 4.0.1.
- Published
- May 25, 2026
- Updated
- Jul 24, 2026
- EPSS
- 0.7% · 55th percentile
- CWE
- CWE-770
Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.7 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · EEF
- 8.7
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| benoitc | hackney | cpe:2.3:a:benoitc:hackney |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- benoitc hackney2.0.0 and later · before 4.0.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (EEF). Independent of NVD's CPE analysis and usually ahead of it.
benoitc hackney
- 2.0.0 and later · before 4.0.1affected · semver
- d9713695c0d99855d12c73fd8a0b4be0543950c4 and later · before 31f6f0e27e096ad88743dfded4f030a3ee74972eaffected · git
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Hex | hackney | from 2.0.0 · before 4.0.1 | 4.0.1 |
Same product
benoitc: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-115693Custom cacerts or cacertfile do not restrict trust to the pinned CA in hackney36Monitor
- CVE-2026-47073Unbounded memory consumption in WebSocket client in hackney34Monitor
- CVE-2026-47066Infinite loop in Alt-Svc header parser in hackney34Monitor
Published before and after this one in the same product
- Later →CVE-2026-47069May 25, 2026 · CRLF injection in cookie domain/path options in hackney8Monitor
- Later →CVE-2026-47070May 25, 2026 · HTTP/3 redirect handler leaks Authorization and Cookie headers to cross-origin redirect target in hackney24Monitor
- Later →CVE-2026-47071May 25, 2026 · SOCKS5 TLS upgrade ignores caller timeout in hackney32Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| benoitc hackney | 31f6f0e27e096ad88743dfded4f030a3ee74972e | Vendor (CNA) |
| benoitc hackney | 4.0.1 | Vendor (CNA) |
| Hex:hackney | 4.0.1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Peter Ullrichfinder
- Benoit Chesneauremediation developer
- Jonatan Männchen / EEFanalyst
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-770 · Allocation of Resources Without Limits or ThrottlingCVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- FloodingCAPEC-125likelihood: High · Medium
- Excessive AllocationCAPEC-130likelihood: Medium · Medium
- XML Ping of the DeathCAPEC-147likelihood: Low · Medium
- Exponential Data ExpansionCAPEC-197likelihood: High · Medium
- Serialized Data Parameter BlowupCAPEC-229likelihood: High · High
- Serialized Data with Nested PayloadsCAPEC-230likelihood: Medium · High
- Oversized Serialized Data PayloadsCAPEC-231likelihood: Medium · High
- HTTP DoSCAPEC-469Low
ATT&CK techniques
- Network Denial of Service:Direct Network FloodT1498.001
- Network Denial of Service:Reflection AmplificationT1498.002
- Endpoint Denial of ServiceT1499
- Endpoint Denial of Service: OS Exhaustion FloodT1499.001
- Endpoint Denial of Service:Service Exhaustion FloodT1499.002
- Endpoint Denial of Service:Application Exhaustion FloodT1499.003
Change log
- Fix✗ → ✓
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References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.