Scriban before 7.5.3 Denial of Service via Unguarded Builtins and Recursion
Scriban 7.5.2 and earlier are affected, in setups using the default TemplateContext with nothing exposed by the host. No vendor rating is given. 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 versions before 7.5.3 are affected by a denial-of-service flaw in which template authors can exhaust memory and CPU, because some built-in functions skip the library's allocation and loop limits. An attacker can reach it remotely, without logging in, by submitting small crafted templates that crash or stall multi-tenant hosts.
Read the original description
Scriban before 7.5.3 contains a resource exhaustion vulnerability that allows untrusted template authors to exhaust memory and CPU because builtins like math.format, regex.replace and string.escape skip the LimitToString allocation guard. Attackers can submit small templates using huge format precision specifiers, shared-structure array comparison, BigInteger multiplication or exponential function recursion that ignore LoopLimit and CancellationToken, crashing or stalling multi-tenant hosts.
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-2026-124437
Is CVE-2026-124437 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?
A single small template from an untrusted author can exhaust host memory or pin a CPU core indefinitely. On shared hosts this can degrade or kill service for other users.Source: github.com
Which versions are affected by CVE-2026-124437?
scriban: before 7.5.3.Source: cve.now feed data
Am I affected, and how do I check?
Scriban 7.5.2 and earlier versions are affected, in setups using the default TemplateContext with nothing exposed by the host. To check, look at the Scriban version in the project's package references and at how the TemplateContext is configured.Source: github.com
How do I fix CVE-2026-124437?
Upgrade Scriban to 7.5.3 or later, which is the listed patched version.Source: github.com