NVD / CVE Program· CNA mitre

CVE-2021-47208: The Mojolicious module before 9.11 for Perl has a bug in format detection that can potentially be exploited for denial of service.

Noroxi assessment

Priority: Monitor (action score 17/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.55% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: libmojolicious-perl (Debian:12) 9.21+dfsg-1.

Low priority for now. Upgrade to libmojolicious-perl (Debian:12) 9.21+dfsg-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

MediumCVSS 4.3 · v3.1—No exploit Fix available

Denial of service

BDU:2024-04336

Published: Apr 7, 2024
Updated: Jun 17, 2026
EPSS: 0.5% · 46th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 17 / 40 · 4.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

CISA SSVC decision

Exploitation: proof of concept
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
mojolicious	mojolicious	cpe:2.3:a:mojolicious:mojolicious

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

mojolicious mojoliciousbefore 9.11

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	libmojolicious-perl	before 9.21+dfsg-1	9.21+dfsg-1

Same product

mojolicious: all records

Other highest-scoring records for the same primary product.

CVE-2010-4803Mojolicious before 0.999927 does not properly implement HMAC-MD5 checksums, which has unspecified impact and remote attack vectors.
41Plan
CVE-2010-4802Commands.pm in Mojolicious before 0.999928 does not properly perform CGI environment detection, which has unspecified impact and remote atta
41Plan
CVE-2009-5074Unspecified vulnerability in the MojoX::Dispatcher::Static implementation in Mojolicious before 0.991250 has unknown impact and attack vecto
40Plan

Published before and after this one in the same product

← EarlierCVE-2011-1589Apr 29, 2011 · Directory traversal vulnerability in Path.pm in Mojolicious before 1.16 allows remote attackers to read arbitrary files via a %2f..%2f (enco
21Monitor
← EarlierCVE-2011-1841May 2, 2011 · Cross-site scripting (XSS) vulnerability in the link_to helper in Mojolicious before 1.12 allows remote attackers to inject arbitrary web sc
18Monitor
Later →CVE-2024-58135May 3, 2025 · Mojolicious versions from 7.28 through 9.45 for Perl will generate weak HMAC session cookie secrets via "mojo generate app" by default
21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:libmojolicious-perl	9.21+dfsg-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

mojolicious/mojocommit a0c4576

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: low · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: Low

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

nvd-secondary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

Fix✗ → ✓Sep 28, 2026, 10:49 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/mojolicious/mojo/commit/a0c4576ffb11c235088550de9ba7ac4196e1953c

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records