NVD / CVE Program· CNA mitre

CVE-2021-32918: An issue was discovered in Prosody before 0.11.9.

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

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: 2.1% (FIRST EPSS); higher than 82% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: prosody (Alpine:v3.12) 0.11.9-r0; prosody (Debian:10) 0.11.2-1+deb10u1; prosody (Debian:12) 0.11.9-1.

Low priority for now. Upgrade to prosody (Alpine:v3.12) 0.11.9-r0; prosody (Debian:10) 0.11.2-1+deb10u1; prosody (Debian:12) 0.11.9-1 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

An issue was discovered in Prosody before 0.11.9. Default settings are susceptible to remote unauthenticated denial-of-service (DoS) attacks via memory exhaustion when running under Lua 5.2 or Lua 5.3.

Published: May 13, 2021
Updated: Jun 16, 2026
EPSS: 2.1% · 82th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 2.1%

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
prosody	prosody	cpe:2.3:a:prosody:prosody
lua	lua	cpe:2.3:a:lua:lua
debian	debian linux	cpe:2.3:o:debian:debian_linux
fedoraproject	fedora	cpe:2.3:o:fedoraproject:fedora

Affected versions

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

debian debian linux10.0
fedoraproject fedora32
fedoraproject fedora33
fedoraproject fedora34
prosody prosodybefore 0.11.9

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Alpine:v3.12	prosody	before 0.11.9-r0	0.11.9-r0
Debian:10	prosody	before 0.11.2-1+deb10u1	0.11.2-1+deb10u1
Debian:12	prosody	before 0.11.9-1	0.11.9-1
openSUSE:Leap 15.2	prosody	before 0.11.9-lp152.2.3.1	0.11.9-lp152.2.3.1
openSUSE:Tumbleweed	prosody	before 0.11.10-1.2	0.11.10-1.2
SUSE:Package Hub 15 SP2	prosody	before 0.11.9-bp152.2.3.1	0.11.9-bp152.2.3.1

Same product

prosody: all records

Other highest-scoring records for the same primary product.

CVE-2018-10847prosody before versions 0.10.2, 0.9.14 is vulnerable to an Authentication Bypass.
35Monitor
CVE-2022-0217It was discovered that an internal Prosody library to load XML based on libexpat does not properly restrict the XML features allowed in…
32Monitor
CVE-2014-2745Prosody before 0.9.4 does not properly restrict the processing of compressed XML elements, which allows remote attackers to cause a denial…
32Monitor

Published before and after this one in the same product

← EarlierCVE-2017-18265May 9, 2018 · Prosody before 0.10.0 allows remote attackers to cause a denial of service (application crash), related to an incompatibility with certain…
31Monitor
← EarlierCVE-2021-32917May 13, 2021 · An issue was discovered in Prosody before 0.11.9.
22Monitor
Later →CVE-2021-32919May 13, 2021 · An issue was discovered in Prosody before 0.11.9.
30Monitor

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
alpine:prosody	0.11.9-r0 · Alpine:v3.12	Package registry (OSV)
debian:prosody	0.11.9-1 · Debian:12	Package registry (OSV)
opensuse:prosody	0.11.9-lp152.2.3.1 · openSUSE:Leap 15.2	Package registry (OSV)
suse:prosody	0.11.9-bp152.2.3.1 · SUSE:Package Hub 15 SP2	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.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

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

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

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

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

nvd-primary

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 (1)

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

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References

www.openwall.com/lists/oss-security/2021/05/13/1

Show all references (7 more)

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

All records