TI-2026-10955 Aliases CVE-2026-12817 GHSA-9q38-7pr7-8j6w

OpenPGP AEAD decryption skips final tag on chunk-aligned data

MEDIUM 43CWE-354Published 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: —
Confidentiality · integrity · availability: None · High · None
Fix status: Partial Red Hat: 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.

Summary

In Bouncy Castle for Java before 1.85, OpenPGP AEAD decryption skips final tag on chunk-aligned data. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bcpg-fips 1.0.13 (1.0.X series), 2.0.13 (2.0.X series) and 2.1.13 (2.1.X series).

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00169 6th 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: 2 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	1.74 to 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	1.0.7 to before 1.0.13; 2.0.0 to before 2.0.13; 2.1.0 to before 2.1.13	1.0.13, 2.0.13, 2.1.13	Patch available	CNA

BC-JAVA VendorLegion of the Bouncy Castle Inc. Affected 1.74 to 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 1.0.7 to before 1.0.13; 2.0.0 to before 2.0.13; 2.1.0 to before 2.1.13 Fixed in 1.0.13, 2.0.13, 2.1.13 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:bcpg-fips::::::::	1.0.7 to before 1.0.13; 2.0.8 to before 2.0.13; 2.1.10 to before 2.1.13	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:bcpg-fips:*:*:*:*:*:*:*:* Versions 1.0.7 to before 1.0.13; 2.0.8 to before 2.0.13; 2.1.10 to before 2.1.13 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 1.0.13, 2.0.13, 2.1.13

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 1.0.13, 2.0.13, 2.1.13
4 records Highest priority Priority MEDIUM 3 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-42544 OpenPGP user-attribute subpacket length bounded only by JVM max memoryPriority MEDIUM 44
- TI-2026-42535 OpenPGP CFB quick-check oracle active on symmetric/session-key pathsPriority MEDIUM 44
- TI-2026-42543 OpenPGP Argon2 S2K honours attacker-chosen memory and passesPriority LOW 31
Show all 4 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: Out of support scope
Red Hat JBoss Enterprise Application Platform 7	Affected	No fix planned: Out of support scope

Timeline

2026-10-02 Threatist record created from CVE-2026-12817
2026-10-03 Alias added: GHSA-9q38-7pr7-8j6w

References

Patch 1

https://github.com/bcgit/bc-java/commit/4b712819846ec944379f4909101abac20f0ad4b0

Advisory 1

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9012817

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

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