# CVE-2026-40942: DSF: Inverted Time Comparison in OIDC JWKS and Token Cache

> Inverted time comparisons in OIDC caches cause excessive network requests and use of expired tokens, leading to potential denial of service and authentication bypass.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-xmj9-7625-f634

## What is CVE-2026-40942?

CVE-2026-40942 is a medium-severity vulnerability in datasharingframework dsf, published on 21 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Data Sharing Framework (DSF) implements a distributed process engine based on the BPMN 2.0 and FHIR R4 standards. Prior to 2.1.0, The OIDC JWKS and Metadata Document caches used an inverted time comparison (isBefore instead of isAfter), causing the cache to never return cached values. Every incoming request triggered a fresh HTTP fetch of the OIDC Metadata Document and JWKS keys from the OIDC provider. The OIDC token cache for the FHIR client connections used an inverted time comparison (isBefore instead of isAfter), causing the cache to never invalidate. Every incoming request returned the same OIDC token even if expired. This vulnerability is fixed in 2.1.0.

Weakness: CWE-670 (Always-Incorrect Control Flow Implementation)

## Which versions are affected by CVE-2026-40942?

4 open source packages ship an affected version, including dev.dsf:dsf-bpe-process-api-v2 and dev.dsf:dsf-bpe-server.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `dev.dsf:dsf-bpe-process-api-v2` | Maven | All versions | None |
| `dev.dsf:dsf-bpe-process-api-v2` | Maven | All versions | None |
| `dev.dsf:dsf-bpe-server` | Maven | All versions | None |
| `dev.dsf:dsf-bpe-server` | Maven | All versions | None |

## How do I fix CVE-2026-40942?

No fix has been published for CVE-2026-40942 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40942 being exploited?

There is no known exploitation of CVE-2026-40942 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40942 and fix it if it is affected.

What it is: CVE-2026-40942 is a medium-severity vulnerability in datasharingframework dsf, published on 21 Apr 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-2026-40942 in the wild and no public exploit code.

Affected packages and fixed versions:
- dev.dsf:dsf-bpe-process-api-v2 (Maven): affected all versions; no fix listed
- dev.dsf:dsf-bpe-process-api-v2 (Maven): affected all versions; no fix listed
- dev.dsf:dsf-bpe-server (Maven): affected all versions; no fix listed
- dev.dsf:dsf-bpe-server (Maven): affected all versions; no fix listed

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-2026-40942/ (Markdown: https://insights.sbomify.com/CVE-2026-40942/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40942
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40942
- OSV: https://osv.dev/vulnerability/CVE-2026-40942

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40942/
Summaries are generated and may contain mistakes; the official description above is the record.