How severe is CVE-2026-12817?

CVE-2026-12817 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.

Is CVE-2026-12817 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-12817?

CVE-2026-12817 primarily affects Bouncycastle Bc-java. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-12817?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-12817 published?

CVE-2026-12817 was published on 2026-08-03 and last updated on 2026-08-31.

CVE-2026-12817

CVE-2026-12817 is a high-severity vulnerability in Bouncycastle Bc-java with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-354.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v4: 8.7
EPSS exploit prediction: 0% (6th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-354
Affected product: Bouncycastle Bc-java
Published: 2026-08-03
Last modified: 2026-08-31

Description

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).

Frequently asked questions

What is CVE-2026-12817?: 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).
How severe is CVE-2026-12817?: CVE-2026-12817 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2026-12817 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (6th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-12817?: CVE-2026-12817 primarily affects Bouncycastle Bc-java. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-12817?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-12817 published?: CVE-2026-12817 was published on 2026-08-03 and last updated on 2026-08-31.

References

Affected products (3)

cpe:2.3:a:bouncycastle:bc-java:*:*:*:*:*:*:*:*
cpe:2.3:a:bouncycastle:bcpg-fips:*:*:*:*:*:*:*:*
cpe:2.3:a:bouncycastle:bouncy_castle_for_java_lts:*:*:*:*:*:*:*:*

More vulnerabilities in Bouncycastle Bc-java

CVE-2007-6721 — Critical (CVSS 10.0): The Legion of the Bouncy Castle Java Cryptography API before release 1.38, as used in Crypto Provider Package before…
CVE-2018-1000613 — Critical (CVSS 9.8): Legion of the Bouncy Castle Legion of the Bouncy Castle Java Cryptography APIs 1.58 up to but not including 1.60…
CVE-2026-58062 — Critical (CVSS 9.1): In Bouncy Castle for Java before 1.85, Stapled OCSP response accepted without binding to the checked certificate. This…
CVE-2026-8763 — Critical (CVSS 9.1): In Bouncy Castle for Java before 1.85, Name Constraints bypass via trailing dot in rfc822Name and URI. This issue also…
CVE-2026-59650 — Critical (CVSS 9.1): In Bouncy Castle for Java before 1.85, MTI/A0 DH agreement exponentiates unvalidated peer value. This issue also…
CVE-2026-12185 — High (CVSS 8.6): In Bouncy Castle for Java before 1.85, BKS/UBER keystore allocates from untrusted lengths before integrity check. This…

All CVEs affecting Bouncycastle Bc-java →

Other CWE-354 vulnerabilities

CVE-2025-11543 — Critical (CVSS 9.8): Improper Validation of Integrity Check Value vulnerability in Sharp Display Solutions projectors allows a attacker may…
CVE-2024-25678 — Critical (CVSS 9.8): In LiteSpeed QUIC (LSQUIC) Library before 4.0.4, DCID validation is mishandled.
CVE-2023-33668 — Critical (CVSS 9.8): DigiExam up to v14.0.2 lacks integrity checks for native modules, allowing attackers to access PII and takeover…
CVE-2017-15994 — Critical (CVSS 9.8): rsync 3.1.3-development before 2017-10-24 mishandles archaic checksums, which makes it easier for remote attackers to…
CVE-2026-75803 — Critical (CVSS 9.1): Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying…
CVE-2026-49230 — Critical (CVSS 9.1): Improper Validation of Integrity Check Value vulnerability in Apache APISIX. The jwe-decrypt plugin under default…

Browse all CWE-354 vulnerabilities →