MEDIUM
CVE-2026-40211
CWE-770Published: June 25, 2026· Updated: Jun 25, 2026
5.3
CVSS v3.1
EPSS:0.41%probability of exploitation in 30 daysPercentile:33.0th
Official Description
An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.
Technical Analysis
CVE-2026-40211 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
All References (1)
Quick Facts
CVE IDCVE-2026-40211
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-770
CISA KEVNo
EPSS (30d)0.41%
PublishedJun 25, 2026
Related CVEs (CWE-770)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-40211 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.