CVE-2026-58226
Unauthenticated denial-of-service via unbounded HPACK integer decoding in hpax
Description
Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding. hpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value <<< m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification. This issue affects hpax from 0.1.1 before 1.0.4.
INFO
Published Date :
July 6, 2026, 11:16 a.m.
Last Modified :
Oct. 25, 2026, 8:10 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update hpax to version 1.0.4 or later.
- Apply vendor patches if available.
- Monitor system resources for unusual activity.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-58226.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-58226 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-58226
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-58226 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-58226 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Translated by [email protected]
Oct. 25, 2026
Action Type Old Value New Value Added Translation Title: hpax de elixir-mint, Description: Una vulnerabilidad de complejidad algorítmica ineficiente en elixir-mint hpax permite una denegación de servicio no autenticada a través de la decodificación de enteros HPACK sin límites. hpax decodifica enteros HPACK de longitud variable sin un límite superior en el valor decodificado o en el número de octetos de continuación. ’Elixir.HPAX.Types’:decode_remaining_integer/3 acumula el entero como int + (value <<< m), desplazando 7 bits más por cada octeto de continuación y deteniéndose solo en un octeto de terminación o entrada truncada, nunca porque el entero se hizo demasiado grande. Debido a que los enteros BEAM son de precisión arbitraria, una secuencia de N octetos de continuación construye un bignum de O(N) bits y se vuelve a añadir a un bignum cada vez más grande en cada paso, por lo que el costo total de decodificación es superlineal (aproximadamente O(N^2)). Un atacante no autenticado que puede enviar un bloque de encabezado HTTP/2 a un servidor que utiliza este decodificador (alcanzado a través del punto de entrada ’Elixir.HPAX’:decode/2) puede proporcionar un pequeño bloque de encabezado que fuerza una gran cantidad de CPU (y memoria transitoria) controlada por el atacante, una amplificación de denegación de servicio. Este problema afecta a hpax desde la versión 0.1.1 anterior a la 1.0.4. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 06, 2026
Action Type Old Value New Value Added Reference https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2 Added SSVC {'id': 'CVE-2026-58226', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-06T12:49:38.954923Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 06, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/elixir-mint/hpax', 'vendor': 'elixir-mint', 'modules': ['Elixir.HPAX', 'Elixir.HPAX.Types'], 'product': 'hpax', 'versions': [{'status': 'affected', 'version': '0.1.1', 'lessThan': '1.0.4', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/hpax', 'packageName': 'hpax', 'programFiles': ['lib/hpax.ex', 'lib/hpax/types.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HPAX':decode/2"}, {'name': "'Elixir.HPAX.Types':decode_integer/2"}, {'name': "'Elixir.HPAX.Types':decode_remaining_integer/3"}]}, {'cpes': ['cpe:2.3:a:elixir-mint:hpax:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/elixir-mint/hpax', 'vendor': 'elixir-mint', 'modules': ['Elixir.HPAX', 'Elixir.HPAX.Types'], 'product': 'hpax', 'versions': [{'status': 'affected', 'version': '56db437a7e2c515e3bdd770ac7947b02cd2390d0', 'lessThan': '1ba4bb2dc91e80089cf89c73970ac3ded76f17eb', 'versionType': 'git'}], 'packageURL': 'pkg:github/elixir-mint/hpax', 'packageName': 'elixir-mint/hpax', 'programFiles': ['lib/hpax.ex', 'lib/hpax/types.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.HPAX':decode/2"}, {'name': "'Elixir.HPAX.Types':decode_integer/2"}, {'name': "'Elixir.HPAX.Types':decode_remaining_integer/3"}]}] Added Description Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding. hpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value <<< m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification. This issue affects hpax from 0.1.1 before 1.0.4. Added CVSS V4.0 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 Added CWE CWE-407 Added Reference https://cna.erlef.org/cves/CVE-2026-58226.html Added Reference https://github.com/elixir-mint/hpax/commit/1ba4bb2dc91e80089cf89c73970ac3ded76f17eb Added Reference https://github.com/elixir-mint/hpax/security/advisories/GHSA-jj2p-32j7-whj2 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-58226