---
title: "CVE-2026-55565: Yamcs vulnerable to authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled by Janino (`LikeExpression`)"
url: https://erroneo.us/security/cve/CVE-2026-55565/
description: "CVE-2026-55565 (org.yamcs:yamcs-core (Maven)): Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCodegetValueReturn…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-28
date_modified: 2026-08-31
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-55565"
kev: false
cvss: 9.9
epss: 0.0065
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-55565: Yamcs vulnerable to authenticated remote code execution via unescaped StreamSQL `LIKE` pattern compiled by Janino (`LikeExpression`)

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.7% , percentile 50: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 50% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes org.yamcs:yamcs-core (Maven) >= 5.13.0, <= 5.13.1, fixed in 5.13.2 ; org.yamcs:yamcs-core (Maven) <= 5.12.7, fixed in 5.12.8 . Check your lockfile, including transitive dependencies.

## What it is

Yamcs is a mission control framework. Prior to 5.12.8 and 5.13.2, Yamcs LikeExpression.fillCodegetValueReturn in yamcs-core/src/main/java/org/yamcs/yarch/streamsql/LikeExpression.java inserts an unescaped LIKE pattern into Java source compiled by Expression.getCompiledExpression through SimpleCompiler.cook instead of applying ValueExpression.escapeJavaString. The pattern can originate from POST /api/archive/{instance}:executeSql, POST /api/archive/{instance}:streamSql, POST /api/archive/{instance}/tables/{table}:readRows, GET /api/archive/{instance}/events, or activity searches, including paths available with ReadTables, ReadEvents, or ReadActivities. A quote in the pattern can inject Java that runs as the Yamcs server process. This issue is fixed in versions 5.12.8 and 5.13.2.

## Affected packages

- Maven `org.yamcs:yamcs-core` >= 5.13.0, <= 5.13.1 → fixed: 5.13.2
- Maven `org.yamcs:yamcs-core` <= 5.12.7 → fixed: 5.12.8

## Affected products (CVE record)

- yamcs yamcs: < 5.12.8, >= 5.13.0, < 5.13.2

## Severity

- GitHub_M CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.65% probability of exploitation activity in the next 30 days; percentile 50.

## Sources

- [GitHub Advisory GHSA-c64q-hj4j-375f](https://github.com/advisories/GHSA-c64q-hj4j-375f)
- [CVE.org record CVE-2026-55565](https://www.cve.org/CVERecord?id=CVE-2026-55565)
- [NVD entry CVE-2026-55565](https://nvd.nist.gov/vuln/detail/CVE-2026-55565)
- [github.com](https://github.com/yamcs/yamcs/security/advisories/GHSA-c64q-hj4j-375f)
- [github.com](https://github.com/yamcs/yamcs/commit/640e1598b7097b521692e89dd47a39b6cb1fc663)
- [github.com](https://github.com/yamcs/yamcs/commit/a8fb4a0693fa62a6eb729b26016d1090dd8b289c)
- [github.com](https://github.com/yamcs/yamcs/releases/tag/yamcs-5.12.8)
- [github.com](https://github.com/yamcs/yamcs/releases/tag/yamcs-5.13.2)

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Source page: https://erroneo.us/security/cve/CVE-2026-55565/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt