Plaintext disclosure via native CTR counter wrap
Published Oct 9, 2026 · Updated Oct 9, 2026
CTR keystream reuse in Bouncy Castle Java LTS before 2.73.13 allows attackers to read plaintext via oversized native packets. The native ctr_pc_process_packet entry point omits IV-derived counter-range validation, repeats keystream after counter wrap, and reports the full input length as successful. Exposure requires Intel native packet encryption with a 13–15-byte IV, input exceeding the remaining counter capacity, and access to the resulting ciphertext; streaming and portable implementations are unaffected.
Summary
What happened
CTR keystream reuse in Bouncy Castle Java LTS before 2.73.13 allows attackers to read plaintext via oversized native packets. The native ctr_pc_process_packet entry point omits IV-derived counter-range validation, repeats keystream after counter wrap, and reports the full input length as successful. Exposure requires Intel native packet encryption with a 13–15-byte IV, input exceeding the remaining counter capacity, and access to the resulting ciphertext; streaming and portable implementations are unaffected.
The record
- CVE
- CVE-2026-71884
- Published
- Oct 9, 2026
- Updated
- Oct 9, 2026
- Vendor
- Legion of the Bouncy Castle Inc.
- Product
- Bouncy Castle Java LTS
- Classifications
- CWE-323
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Oct 9, 2026CVE publishedPublication date reported by the CVE source.
- Oct 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2.73.4 <2.73.13
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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