A mis-handling of invalid unicode characters in the Java implementation of Tink versions prior to 1.5 allows an attacker to change the ID part of a ciphertext, which result in the creation of a second ciphertext that can decrypt to the same plaintext. This can be a problem with encrypting deterministic AEAD with a single key, and rely on a unique ciphertext-per-plaintext.
CVE-2020-8929
This medium-severity CVE scores 5.3 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.3
- EG Score
- 5.3(low)
- EPSS
- 37.5%
- KEV
- Not listed
Published
October 19, 2020
Last Modified
June 5, 2025
References (4)
- cve-coordination@googlehttps://github.com/google/tink/commit/93d839a5865b9d950dffdc9d0bc99b71280a8899
- cve-coordination@googlehttps://github.com/google/tink/security/advisories/GHSA-g5vf-v6wf-7w2r
- af854a3a-2127-422b-91ae-364da2661108https://github.com/google/tink/commit/93d839a5865b9d950dffdc9d0bc99b71280a8899
- af854a3a-2127-422b-91ae-364da2661108https://github.com/google/tink/security/advisories/GHSA-g5vf-v6wf-7w2r
Affected Packages
(2 across 2 ecosystems)
Maven(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| com.google.crypto.tink:tink | 1.0.0 ... 1.4.0-rc2 (17 versions) | 1.5.0 | — |
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| tink | 1.4.0 | 1.5.0 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 48× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-12 05:44 UTCEPSS rescore
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- 2026-06-25 13:48 UTCEPSS rescore
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- 2026-05-23 06:31 UTCEG score recompute
Frequently asked(5)
What is CVE-2020-8929?
When was CVE-2020-8929 disclosed?
Is CVE-2020-8929 actively exploited?
What is the CVSS score of CVE-2020-8929?
How do I remediate CVE-2020-8929?
Dependency Blast Radius
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