# kas's late signature validation may allow unnoticed repository manipulations

Advisory record · `GHSA-4vqc-wpwg-vh7j`

- **Identifiers:** `GHSA-4vqc-wpwg-vh7j` · `CVE-2026-47192` · `PYSEC-2026-2543`
- **State:** Confirmed
- **Severity:** CVSS 2.1 Low
- **Critical:** No
- **Weakness (CWE):** [CWE-347](https://cwe.mitre.org/data/definitions/347.html)
- **Tags:** [Weak cryptography or TLS](https://agentprime.io/advisories/tag/weak-crypto.md)
- **Published:** 4 Jun 2026
- **Updated:** 15 Aug 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 4 Jun 2026, 17:36 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `kas` (PyPI): affected `>=4.8, <5.3`; fixed in `5.3`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Kas versions 4.8 up to but not including 5.3 have a signature validation flaw: included configuration is processed before repository signatures are checked, so an attacker who controls a referenced repository may be able to replace the key used to verify a tag signature. Exploiting this requires several specific conditions, including a tag reference without a commit ID and a key stored in a repository without a pinned fingerprint. Upgrade kas to version 5.3 or later. As a workaround, pin the expected signature key by its fingerprint.

Written 5 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 2.1 Low, CVSS 4.0: `CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0025, the 17th percentile, on 12 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:40 UTC: First seen by agentprime
- 31 Oct 2026, 14:40 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-4vqc-wpwg-vh7j)

## Sources

- [GitHub Advisory Database: GHSA-4vqc-wpwg-vh7j](https://github.com/advisories/GHSA-4vqc-wpwg-vh7j)
- [OSV: GHSA-4vqc-wpwg-vh7j](https://osv.dev/vulnerability/GHSA-4vqc-wpwg-vh7j)
- <https://github.com/siemens/kas/security/advisories/GHSA-4vqc-wpwg-vh7j>
- <https://github.com/siemens/kas/security/advisories/GHSA-qjwp-hrq6-r26r>
- <https://github.com/siemens/kas/commit/4cb4a3d01122ffaec9feaae768a5814092f6f9b5>
- <https://github.com/siemens/kas/commit/5b2114becfc154b16ef496d24f8c2191a2297f57>
- <https://github.com/siemens/kas>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-4vqc-wpwg-vh7j>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-4vqc-wpwg-vh7j/>. Everything for agents: <https://agentprime.io/llms.txt>.