Chartbrew: Private chart data disclosure via forgeable CB_SECRET share tokens
Only Chartbrew server 5.2.2 or earlier is affected, and only installs using a known or default CB_SECRET, such as source installs or the repo docker compose setup. Fixed in 5.2.3.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 5.2.3
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- 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? →
- 30/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- 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
Chartbrew, an open-source app for building charts from databases and APIs, has a flaw in how it verifies share tokens that lets an attacker read private chart data, including chart contents, without a legitimate share link, if the deployment's CB_SECRET is known or left at a shipped default. The attack can be carried out remotely without logging in by forging tokens for sequential chart IDs, but only for private charts that have been shared at least once.
Read the original description
Chartbrew is an open-source web application that can connect directly to databases and APIs and use the data to create charts. Prior to 5.2.3, Chart share and embed tokens were signed with CB_SECRET, including known or shipped-default values in stock source and repository Docker Compose installs. The vulnerable surface is chart share-token verification and filter-access routes for private charts. An attacker who knows the deployment's CB_SECRET targets a private chart that has been shared at least once so a share-policy row exists, then forges a Chart-subject token for that chart id. The known signing key permits valid Chart tokens, and the filter-access path accepts sequential integer ids without requiring a legitimate share link; token expiry and revocation are ineffective once the secret is known. The condition requires a known or default secret and an existing share-policy row. A bare container where CB_SECRET is undefined is outside this path, and a unique secret excludes it only while the value remains unknown and unpredictable. An unauthenticated attacker can enumerate integer ids and read arbitrary private chart data, including chartData, without possessing a legitimate share link. This issue is fixed in version 5.2.3.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure22/25Default setups, reachable over the network without a login
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.5/10CVSS 7.5
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 5.2.3.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- chartbrew chartbrew
fixed in 5.2.3
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-2026-85708
Is CVE-2026-85708 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
What does this mean?
Chartbrew signs share tokens with CB_SECRET. When that secret is known or default, a share token can be forged, which can expose data from private charts to anonymous visitors, including values reachable through the chart's query.Source: github.com
Which versions are affected by CVE-2026-85708?
chartbrew: before 5.2.3.Source: cve.now feed data
Am I affected, and how do I check?
Affected are Chartbrew server versions 5.2.2 and earlier, on installs that use a known or default CB_SECRET, such as source installs or the repo docker compose setup. Only charts shared at least once are in scope, because a share policy row must exist. Check the server version and whether CB_SECRET is still the default value in the install configuration.Source: github.com
How do I fix CVE-2026-85708?
Upgrade the Chartbrew server to 5.2.3, the listed fixed version.Source: github.com