CVE-2026-12852
MLS wire decoder allocates attacker-declared opaque length before bounds check
Description
In Bouncy Castle for Java before 1.85, MLS wire decoder allocates attacker-declared opaque length before bounds check.
INFO
Published Date :
Aug. 3, 2026, 4:16 a.m.
Last Modified :
Aug. 28, 2026, 4:16 p.m.
Remotely Exploit :
Yes !
Source :
91579145-5d7b-4cc5-b925-a0262ff19630
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | 91579145-5d7b-4cc5-b925-a0262ff19630 | ||||
| CVSS 4.0 | HIGH | 91579145-5d7b-4cc5-b925-a0262ff19630 |
Solution
- Update Bouncy Castle for Java to 1.85 or newer.
- Apply vendor-provided security patches.
- Review and validate length checks.
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-2026-12852.
| URL | Resource |
|---|---|
| https://github.com/bcgit/bc-java/commit/a747038bb5bbd5e29fb2b7607ab38af1fd8d1790 | Patch |
| https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012852 | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12852 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-2026-12852
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-2026-12852 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12852 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]
Aug. 28, 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:bouncycastle:bc-java:*:*:*:*:*:*:*:* versions up to (excluding) 1.85 Added Reference Type bcorg: https://github.com/bcgit/bc-java/commit/a747038bb5bbd5e29fb2b7607ab38af1fd8d1790 Types: Patch Added Reference Type bcorg: https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012852 Types: Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 03, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-12852', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-03T15:11:15.405624Z'} -
CVE Modified by 91579145-5d7b-4cc5-b925-a0262ff19630
Aug. 03, 2026
Action Type Old Value New Value Added Reference https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012852 Removed Reference https://github.com/bcgit/bc-java/wiki/CVE-2026-12852 -
New CVE Received by 91579145-5d7b-4cc5-b925-a0262ff19630
Aug. 03, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/bcgit/bc-java', 'vendor': 'Legion of the Bouncy Castle Inc.', 'modules': ['mls'], 'product': 'BC-JAVA', 'versions': [{'status': 'affected', 'version': '1.73', 'lessThan': '1.85', 'versionType': 'maven'}], 'platforms': ['all'], 'packageURL': 'pkg:maven/org.bouncycastle/bcmls-jdk18on', 'packageName': 'bcmls', 'programFiles': ['MLSInputStream'], 'collectionURL': 'https://www.bouncycastle.org/download/bouncy-castle-java/', 'defaultStatus': 'unaffected'}] Added Description In Bouncy Castle for Java before 1.85, MLS wire decoder allocates attacker-declared opaque length before bounds check. 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:Amber Added CWE CWE-789 Added Reference https://github.com/bcgit/bc-java/commit/a747038bb5bbd5e29fb2b7607ab38af1fd8d1790 Added Reference https://github.com/bcgit/bc-java/wiki/CVE-2026-12852