CVE-2026-110499
Client-chosen HPACK encoder table size is applied uncapped, growing per-connection state with every response in Bandit
Description
Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to grow per-connection memory and CPU cost without bound via a large SETTINGS_HEADER_TABLE_SIZE. Bandit resizes its HPACK encoder table to whatever size the client advertises, up to 2^32-1 bytes, and indexes response headers into it. Because responses carry distinct values such as date or content-length, nothing is evicted and the table grows with every response for the life of the connection, while each lookup scans it linearly. The SETTINGS handling in Bandit.HTTP2.Connection (lib/bandit/http2/connection.ex) passes remote_settings.header_table_size to HPAX.resize/2 with no server-side cap, and encode_headers encodes every response header as :store. Serving N responses on one connection therefore costs O(N²) CPU in the connection process. This issue affects bandit: from 0.3.6 before 1.14.0.
INFO
Published Date :
Oct. 26, 2026, 2:16 p.m.
Last Modified :
Oct. 26, 2026, 4:59 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 bandit to version 1.14.0 or later.
- Limit the maximum header table size on the server.
- Implement connection-level resource throttling.
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-2026-110499.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-110499 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-2026-110499
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).
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The following list is the news that have been mention
CVE-2026-110499 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-110499 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 Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Oct. 26, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-110499', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-10-26T15:02:00.207666Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Oct. 26, 2026
Action Type Old Value New Value Added Description Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to grow per-connection memory and CPU cost without bound via a large SETTINGS_HEADER_TABLE_SIZE. Bandit resizes its HPACK encoder table to whatever size the client advertises, up to 2^32-1 bytes, and indexes response headers into it. Because responses carry distinct values such as date or content-length, nothing is evicted and the table grows with every response for the life of the connection, while each lookup scans it linearly. The SETTINGS handling in Bandit.HTTP2.Connection (lib/bandit/http2/connection.ex) passes remote_settings.header_table_size to HPAX.resize/2 with no server-side cap, and encode_headers encodes every response header as :store. Serving N responses on one connection therefore costs O(N²) CPU in the connection process. This issue affects bandit: from 0.3.6 before 1.14.0. 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-770 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/110xxx/CVE-2026-110499.json">CVE-2026-110499</a> Added Reference https://cna.erlef.org/cves/CVE-2026-110499.html Added Reference https://github.com/mtrudel/bandit/commit/0e68313fab9d204257ebad5c447e4cd9cea8e0ea Added Reference https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a Added Reference https://github.com/mtrudel/bandit/security/advisories/GHSA-47x4-3fxf-82fr Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-110499