High severity · published Sep 22, 2026
CVE-2026-94450
Potential denial of service when configured to send Retry packets in s2n-quic
7.5
CVSS
1.9%
EPSS
No
On KEV
Description
Improper validation of the Destination Connection ID length in s2n-quic 1.88.0 and earlier may allow an unauthenticated remote user to cause a denial of service by shutting down a server endpoint via a single crafted UDP datagram. Only server endpoints specifically configured to send Retry packets are affected.
To remediate this issue, users should upgrade to version v1.89.0 or later.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.9% · higher than 80% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
S2
s2n-quic · AWS
through 1.88.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-94450
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-94450
aws.amazon.com
https://aws.amazon.com/security/security-bulletins/2026-116-aws/
github.com
https://github.com/aws/s2n-quic/releases/tag/v1.89.0
github.com
https://github.com/aws/s2n-quic/security/advisories/GHSA-5rw2-6x5m-v22x
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