NVD / CVE Program· CNA cloudflare

CVE-2023-6193: Unbounded queuing of path validation messages in cloudflare-quiche

Noroxi assessment

Priority: Monitor (action score 21/100)

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: 0.76% (FIRST EPSS); higher than 55.7% 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: quiche (crates.io) 0.19.1.

Low priority for now. Upgrade to quiche (crates.io) 0.19.1 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

quiche v. 0.15.0 through 0.19.0 was discovered to be vulnerable to unbounded queuing of path validation messages, which could lead to excessive resource consumption. QUIC path validation (RFC 9000 Section 8.2) requires that the recipient of a PATH_CHALLENGE frame responds by sending a PATH_RESPONSE. An unauthenticated remote attacker can exploit the vulnerability by sending PATH_CHALLENGE frames and manipulating the connection (e.g. by restricting the peer's congestion window size) so that PATH_RESPONSE frames can only be sent at the slower rate than they are received; leading to storage of path validation data in an unbounded queue. Quiche versions greater than 0.19.0 address this problem.

MediumCVSS 5.3 · v3.1—No exploit Fix available

GHSA-w3vp-jw9m-f9pm

Published: Dec 12, 2023
Updated: Jun 17, 2026
EPSS: 0.7% · 55th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.7%

CNA vs NVD score

NVD: 5.3
CNA · cloudflare: 5.3; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

If any of these changes, we'll tell you in the daily email digest.

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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
cloudflare	quiche	cpe:2.3:a:cloudflare:quiche

Affected versions

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

cloudflare quiche0.15.0 and later · up to 0.19.0 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (cloudflare). Independent of NVD's CPE analysis and usually ahead of it.

Cloudflare quiche
- 0.15.0 and later · up to and including 0.19.0affected · semver

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
crates.io	quiche	from 0.15.0 · before 0.19.1	0.19.1

Same product

cloudflare: all records

Other highest-scoring records for the same primary product.

CVE-2025-7054Infinite loop triggered by connection ID retirement
34Monitor
CVE-2026-12707Unbounded path event queue growth in quiche via peer-driven source connection ID rotation
30Monitor
CVE-2026-12523Resource exhaustion in quiche HTTP/3 and QPACK layers
30Monitor

Published before and after this one in the same product

Later →CVE-2024-1410Mar 12, 2024 · Unbounded storage of information related to connection ID retirement, in quiche
21Monitor
Later →CVE-2024-1765Mar 12, 2024 · Unlimited resource allocation by QUIC CRYPTO frames flooding in quiche
30Monitor
Later →CVE-2025-4820Jun 18, 2025 · Incorrect congestion window growth by optimistic ACK
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
crates.io:quiche	0.19.1	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.

No commit or PR link among the references.

Credits

All researchers

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

Marten Seemannfinder

Variant candidates

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

CVE-2024-176591 days apartUnlimited resource allocation by QUIC CRYPTO frames flooding in quiche
30Monitor
CVE-2024-141091 days apartUnbounded storage of information related to connection ID retirement, in quiche
21Monitor

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

Cloudflare Public Bug BountyHackerOne · paid

The product’s vendor appears in a public program. Matched by name; verify the scope text in the 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: low · 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: Low

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:L

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}