How severe is CVE-2023-6193?

CVE-2023-6193 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2023-6193 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-6193?

CVE-2023-6193 affects Cloudflare Quiche. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-6193?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-6193 published?

CVE-2023-6193 was published on 2023-12-12 and last updated on 2026-06-17.

CVE-2023-6193

CVE-2023-6193 is a medium-severity vulnerability in Cloudflare Quiche with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Cloudflare Quiche
Published: 2023-12-12
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2023-6193?: 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.
How severe is CVE-2023-6193?: CVE-2023-6193 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2023-6193 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-6193?: CVE-2023-6193 affects Cloudflare Quiche. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-6193?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-6193 published?: CVE-2023-6193 was published on 2023-12-12 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:cloudflare:quiche:*:*:*:*:*:*:*:*

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