TI-2026-42541 Aliases CVE-2026-59646 GHSA-4m8h-6737-hrw6

DTLS handshake reassembler allocates buffer from unchecked 24-bit length

MEDIUM 44CWE-789Published 2026-08-03 · Updated 2026-08-03

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 5 fixed, 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-789.

Summary

In Bouncy Castle for Java before 1.85, DTLS handshake reassembler allocates buffer from unchecked 24-bit length. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00465 40th percentileScored 2026-11-07

Fix Partial BC-JAVA (Legion of the Bouncy Castle Inc.): 1.85BC-LTS-JAVA (Legion of the Bouncy Castle Inc.): 2.73.12+1 more productRed Hat: 4 advisoriesRed Hat: 5 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Legion of the Bouncy Castle Inc.	BC-JAVA	before 1.85	1.85	Patch available	CNA
Legion of the Bouncy Castle Inc.	BC-LTS-JAVA	2.73.0 to before 2.73.12	2.73.12	Patch available	CNA
Legion of the Bouncy Castle Inc.	BC-FJA	1.0.0 to before 1.0.24; 2.0.0 to before 2.0.24; 2.1.0 to before 2.1.24	1.0.24, 2.0.24, 2.1.24	Patch available	CNA

BC-JAVA VendorLegion of the Bouncy Castle Inc. Affected before 1.85 Fixed in 1.85 Patch available CNA
BC-LTS-JAVA VendorLegion of the Bouncy Castle Inc. Affected 2.73.0 to before 2.73.12 Fixed in 2.73.12 Patch available CNA
BC-FJA VendorLegion of the Bouncy Castle Inc. Affected 1.0.0 to before 1.0.24; 2.0.0 to before 2.0.24; 2.1.0 to before 2.1.24 Fixed in 1.0.24, 2.0.24, 2.1.24 Patch available CNA

CPE configurations NVD · 3

CPE	Versions	Role	Vendor
cpe:2.3:a:bouncycastle:bc-java::::::::	before 1.85	Vulnerable	Legion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bctls-fips::::::::	before 1.0.24; 2.0.19 to before 2.0.24; 2.1.20 to before 2.1.24	Vulnerable	Legion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts::::::::	up to 2.73.11	Vulnerable	Legion of the Bouncy Castle Inc.

cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:* Versions before 1.85 Vulnerable ·Legion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bctls-fips:*:*:*:*:*:*:*:* Versions before 1.0.24; 2.0.19 to before 2.0.24; 2.1.20 to before 2.1.24 Vulnerable ·Legion of the Bouncy Castle Inc.
cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:* Versions up to 2.73.11 Vulnerable ·Legion of the Bouncy Castle Inc.

Remediation

Fix · CNA BC-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 1.85
Fix · CNA BC-LTS-JAVA (Legion of the Bouncy Castle Inc.) Fixed in 2.73.12
Fix · CNA BC-FJA (Legion of the Bouncy Castle Inc.) Fixed in 1.0.24, 2.0.24, 2.1.24

Red Hat 4 advisories

RHSA-2026:92859 Released 2026-10-29 · Red Hat rating Important
Satellite 6.17 security update
- Red Hat Satellite 6.17 for RHEL 9 openvox-agent-8.31.1-1.el9sat, openvox-server-8.17.0-1.el9sat, yggdrasil-worker-forwarder-0.1.1-1.el9sat
RHSA-2026:92861 Released 2026-10-29 · Red Hat rating Critical
Satellite 6.19 security update
- Red Hat Satellite 6.19 for RHEL 9 openvox-agent-8.31.1-1.el9sat, openvox-server-8.17.0-1.el9sat, python3.12-brotli-1.2.1-1.el9pc +6
RHSA-2026:92858 Released 2026-10-29 · Red Hat rating Important
Satellite 6.16 EUS security update
- Red Hat Satellite 6.16 for RHEL 8 openvox-agent-8.31.1-1.el8sat, openvox-server-8.17.0-1.el8sat, yggdrasil-worker-forwarder-0.1.1-1.el8sat
- Red Hat Satellite 6.16 for RHEL 9 openvox-agent-8.31.1-1.el9sat, openvox-server-8.17.0-1.el9sat, yggdrasil-worker-forwarder-0.1.1-1.el9sat

Show 1 more Red Hat advisories

RHSA-2026:92860 Released 2026-10-29 · Red Hat rating Important
Satellite 6.18 security update
- Red Hat Satellite 6.18 for RHEL 9 openvox-agent-8.31.1-1.el9sat, openvox-server-8.17.0-1.el9sat, yggdrasil-worker-forwarder-0.1.1-1.el9sat

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-08-03
Legion of the Bouncy Castle BC-JAVA 1.85
32 records Highest priority Priority MEDIUM 23 MEDIUM, 9 LOW
Other records, highest priority first
- TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-inPriority MEDIUM 48
- TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
Show all 32 records →
Release · 2026-08-03
Legion of the Bouncy Castle BC-LTS-JAVA 2.73.12
28 records Highest priority Priority MEDIUM 20 MEDIUM, 8 LOW
Other records, highest priority first
- TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer valuePriority MEDIUM 48
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-inPriority MEDIUM 48
- TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificatePriority MEDIUM 48
Show all 28 records →

Show 1 more group

Release · 2026-08-03
Legion of the Bouncy Castle BC-FJA 1.0.24, 2.0.24, 2.1.24
2 records Highest priority Priority MEDIUM 2 MEDIUM
Other records, highest priority first
- TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-inPriority MEDIUM 48
Show all 2 records →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Fuse 7	Affected	No fix planned: Will not fix
Red Hat Satellite 6.16 for RHEL 8	Fixed	RHSA-2026:92858
Red Hat Satellite 6.16 for RHEL 9	Fixed	RHSA-2026:92858
Red Hat Satellite 6.17 for RHEL 9	Fixed	RHSA-2026:92859
Red Hat Satellite 6.18 for RHEL 9	Fixed	RHSA-2026:92860
Red Hat Satellite 6.19 for RHEL 9	Fixed	RHSA-2026:92861

Not affected: 5 products

Red Hat Satellite 6.16 for RHEL 8
Red Hat Satellite 6.16 for RHEL 9
Red Hat Satellite 6.17 for RHEL 9
Red Hat Satellite 6.18 for RHEL 9
Red Hat Satellite 6.19 for RHEL 9

Timeline

2026-10-02 Threatist record created from CVE-2026-59646
2026-10-03 Alias added: GHSA-4m8h-6737-hrw6
2026-10-30 Fix available: RHSA-2026:92858 · Red Hat
2026-10-30 Fix available: RHSA-2026:92859 · Red Hat
2026-10-30 Fix available: Red Hat Satellite 6.16 for RHEL 8, Red Hat Satellite 6.16 for RHEL 9, Red Hat Satellite 6.17 for RHEL 9 +1 · Red Hat
2026-10-30 Fix available: RHSA-2026:92860 · Red Hat
2026-10-30 Fix available: Red Hat Satellite 6.19 for RHEL 9 · Red Hat
2026-10-31 Fix available: RHSA-2026:92861 · Red Hat

References

Patch 2

Advisory 1

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059646

TI-2018-15967 Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to… CVSS 3.1CRITICAL 9.8
TI-2017-09736 BouncyCastle JCE TLS Bleichenbacher/ROBOT CVSS 3.0HIGH 7.5
TI-2026-42545 MTI/A0 DH agreement exponentiates unvalidated peer value CVSS 4.0CRITICAL 9.3
TI-2026-42533 JSSE hostname verifier CN-fallback enabled by default despite documented opt-in CVSS 4.0CRITICAL 9.3
TI-2026-41816 Stapled OCSP response accepted without binding to the checked certificate CVSS 4.0CRITICAL 9.3
TI-2026-07701 Name Constraints bypass via trailing dot in rfc822Name and URI CVSS 4.0CRITICAL 9.3

See all 52 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences