Kroki Mermaid companion SSRF via flowchart image URLs
- Exploited
- No known exploitation
- Fix
- Fixed in 0.31.2
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.31.2.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 8/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Kroki's optional Mermaid companion, when rendering PNG output, can be made to send HTTP or HTTPS GET requests to targets chosen by an attacker through flowchart image URLs, and this happens even when KROKI_SAFE_MODE is set to secure. An attacker can do this remotely by submitting Mermaid source, which requires low-privilege login per the deployment's configuration, and the demonstrated impact is limited to blind requests and possibly triggering state-changing GET endpoints on hosts the companion can reach.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Kroki creates diagrams from textual descriptions. From 0.26.0 until 0.31.2, the optional Mermaid companion's mermaid/src/worker.js renders attacker-controlled flowchart image nodes in headless Chromium without a network request policy, even when KROKI_SAFE_MODE is set to secure. An actor who can submit Mermaid source and satisfy any authentication or authorization configured by the deployment can cause the companion to issue HTTP or HTTPS GET requests when requesting PNG output. Exploitation requires the Mermaid companion, PNG rendering through its headless Chromium process, a diagram-submission path available to the actor, and network reachability from the companion to the target. The demonstrated impact is limited to blind request reachability and possible state-changing GET endpoints; response exfiltration, cloud metadata access, port scanning, and access beyond the companion's network reachability are not established. This issue is fixed in version 0.31.2.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure3/25Reachable over the network · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5/10CVSS 5.0
- No patch0/5No signal
What would change the score
- Would score about 63 if added to CISA KEV
- Would score about 58 if CISA's SSVC rates exploitation active
- Would score about 27 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.31.2.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- yuzutech kroki
From 0.26.0 · fixed in 0.31.2
Evidence 3
- Advisory
- Repository
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-102356
Is CVE-2026-102356 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-102356?
kroki: from 0.26.0 before 0.31.2.Source: cve.now feed data
How do I fix CVE-2026-102356?
Upgrade to a fixed version: 0.31.2.Source: cve.now feed data