CVE Explorer

CVE-2026-44452

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. Prior to commit 8dc37cb, when h2o receives a ClientHello message over TLS or QUIC and it contains a zero-length SNI extension, the h2o server runs over the zero-length hostname while trying to copy the hostname, assuming that it is NULL-terminated. This is a potential denial-of-service attack vector in sense that it might trigger segmentation violation. This issue has been fixed by commit 8dc37cb.

Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:165bf78ccff7b1557d566a92e2bd792f628d98adec8268dcfd309fb1baebc8cb

Known exploited

Not asserted

Disputed

Stale source

Conflicts

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-170","description":"CWE-170: Improper Null Termination","lang":"en","type":"CWE"}

cve_program_cvelist_v5cwe
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/problemTypes/1/descriptions/0

{"cweId":"CWE-125","description":"CWE-125: Out-of-bounds Read","lang":"en","type":"CWE"}

cve_program_cvelist_v5cwe
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/problemTypes/0/descriptions/0

Affected products and versions

1 source assertion

{"product":"h2o","vendor":"h2o","versions":[{"status":"affected","version":"< 8dc37cb"}]}

cve_program_cvelist_v5affected
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion

{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"metric_type":"cvssV3_1"}

cve_program_cvelist_v5cvss
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions

{"cweId":"CWE-170","description":"CWE-170: Improper Null Termination","lang":"en","type":"CWE"}

cve_program_cvelist_v5cwe
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/problemTypes/1/descriptions/0

{"cweId":"CWE-125","description":"CWE-125: Out-of-bounds Read","lang":"en","type":"CWE"}

cve_program_cvelist_v5cwe
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/problemTypes/0/descriptions/0

Source references

2 source assertions

{"name":"https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3","tags":["x_refsource_MISC"],"url":"https://github.com/h2o/h2o/commit/8dc37cb1e6171f7f772667618ea440696fed82c3"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/references/1

{"name":"https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq","tags":["x_refsource_CONFIRM"],"url":"https://github.com/h2o/h2o/security/advisories/GHSA-w68q-rqwx-7wvq"}

cve_program_cvelist_v5reference
urn:baitaphish:normalized-source-record:v2:be81ffe972fc0ca94107db9de0766158caadd707c84fe33647a6a3bd36385312 · sha256:476fd3f8904d50eb… · /containers/cna/references/0

Attribution and limitations

CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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