CVE-2026-76956
Libexpat Insufficient Entropy Denial of Service Vulnerability
Description
In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code leads to insufficient entropy, which results in being vulnerable to hash flooding attacks, causing a denial of service via crafted XML content.
INFO
Published Date :
Aug. 20, 2026, 5:16 a.m.
Last Modified :
Sept. 8, 2026, 9:08 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 8254265b-2729-46b6-b9e3-3dfca2d5bfca | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update libexpat to version 2.8.4 or later.
- Ensure getentropy return codes are properly handled.
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-2026-76956.
| URL | Resource |
|---|---|
| https://github.com/libexpat/libexpat/pull/1326 | Issue Tracking Patch |
| https://github.com/libexpat/libexpat/pull/1329 | Issue Tracking Patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-76956 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-2026-76956
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-2026-76956 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-76956 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.
-
Initial Analysis by [email protected]
Sep. 08, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:* versions from (including) 2.8.2 up to (excluding) 2.8.4 Added Reference Type MITRE: https://github.com/libexpat/libexpat/pull/1326 Types: Issue Tracking, Patch Added Reference Type MITRE: https://github.com/libexpat/libexpat/pull/1329 Types: Issue Tracking, Patch -
CVE Modified by [email protected]
Aug. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Removed CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added Reference https://github.com/libexpat/libexpat/pull/1329 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 20, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-76956', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-20T15:05:31.739781Z'} -
New CVE Received by [email protected]
Aug. 20, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'libexpat project', 'product': 'libexpat', 'versions': [{'status': 'affected', 'version': '2.8.2', 'lessThan': '2.8.4', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added Description In libexpat 2.8.2 and 2.8.3 before 2.8.4, misinterpretation of getentropy's return code leads to insufficient entropy, which results in being vulnerable to hash flooding attacks, causing a denial of service via crafted XML content. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-394 Added Reference https://github.com/libexpat/libexpat/pull/1326