Vulnerability · Published Oct 19, 2020 · Assigned by Google

CVE-2020-8929Ciphertext integrity weakness in Tink

Medium 5.3

In plain English

A medium-severity security flaw in Tink from Google LLC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium

Exploit odds (30 days)0.5%top 59.7% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Maven	com.google.crypto.tink:tink	1.5.0	GHSA-g5vf-v6wf-7w2r
PyPI	tink	1.5.0	PYSEC-2020-142

Affected products (as reported)

Vendor	Product	Versions
Google LLC	Tink	stable – before 1.5

Weakness: CWE-176 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References

https://github.com/google/tink/commit/93d839a5865b9d950dffdc9d0bc99b71280a8899 x_refsource_CONFIRM
https://github.com/google/tink/security/advisories/GHSA-g5vf-v6wf-7w2r x_refsource_CONFIRM