Scriban before 7.5.3 Denial of Service via Uncatchable StackOverflowException
Scriban and Scriban.Signed 7.5.2 and earlier are affected, including default ParserOptions and a new TemplateContext. No vendor rating is given, only the CVSS score of 8.7. Fixed in 7.5.3.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 7.5.3
- 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? →
- 31/100 · 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
Scriban (and Scriban.Signed) before 7.5.3 can be crashed remotely, without logging in, by an attacker who can supply a template, because several recursion paths skip the library's depth limits. A successful attack terminates the host process entirely, causing a denial of service.
Read the original description
Scriban and Scriban.Signed before 7.5.3 contain uncontrolled recursion flaws in which postfix member, indexer, and call chains bypass ExpressionDepthLimit, array comparison lacks depth and cycle checks, and object.eval bypasses RecursiveLimit. Attackers who can supply templates can trigger an uncatchable StackOverflowException that terminates the host process.
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
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 71 if added to CISA KEV
- Would score about 66 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 7.5.3.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- scriban scriban
fixed in 7.5.3
Evidence 2
- Advisory
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-124439
Is CVE-2026-124439 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?
Scriban can be made to recurse until the .NET stack overflows. That crash is uncatchable, so the whole host process terminates and every other request and tenant in it goes down with it.Source: github.com
Which versions are affected by CVE-2026-124439?
scriban: before 7.5.3.Source: cve.now feed data
Am I affected, and how do I check?
Scriban or Scriban.Signed versions 7.5.2 and earlier. Default ParserOptions and a new TemplateContext are sufficient, with no special host configuration needed. For the object.eval path, the host must also pass strings to object.eval or object.eval_template. Check the Scriban package version in the project's package references to see which version is installed.Source: github.com
How do I fix CVE-2026-124439?
Upgrade Scriban to 7.5.3 or later, which is the patched version.Source: github.com