# CVE-2026-15432: Observable Timing Discrepancy in Tink-Java and Tink-Android ChunkedMacVerification

> Attackers can exploit timing side channels in Tink's ChunkedMacVerification to recover valid MAC tags byte-by-byte, compromising message integrity.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Jul 2026
- **Updated:** 22 Jul 2026
- **Also known as:** GHSA-xxmf-j3rw-f8p2

## What is CVE-2026-15432?

CVE-2026-15432 is a high-severity vulnerability in Google Tink-Android, published on 21 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When verifying a mac with a ChunkedMacVerification object, Tink compares the resulting tag with non constant time comparison. This potentially allows an attacker to use timinig information as a side channel in order to get information how many bytes of a given tag match the correct tag. This in turn could allow to find a correct tag bytewise.

Weakness: CWE-208 (Observable Timing Discrepancy)

## Which versions are affected by CVE-2026-15432?

It affects 1 product.


Products: Google Tink Java.

## How do I fix CVE-2026-15432?

No fix has been published for CVE-2026-15432 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15432 being exploited?

There is no known exploitation of CVE-2026-15432 in the wild and no public exploit code.

## Other vulnerabilities in Google Tink-Android

- [CVE-2020-8929](https://insights.sbomify.com/CVE-2020-8929/): Ciphertext integrity weakness in Tink (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15432 and fix it if it is affected.

What it is: CVE-2026-15432 is a high-severity vulnerability in Google Tink-Android, published on 21 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15432 in the wild and no public exploit code.

Affected product: Google Tink-Android. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15432/ (Markdown: https://insights.sbomify.com/CVE-2026-15432/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15432
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15432
- OSV: https://osv.dev/vulnerability/CVE-2026-15432

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15432/
Summaries are generated and may contain mistakes; the official description above is the record.