CVE-2017-10908
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedH2O version 2.2.3 and earlier allows remote attackers to cause a denial of service in the server via specially crafted HTTP/2 header.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceH2O web server versions 2.2.3 and earlier contain a denial-of-service vulnerability triggered by specially crafted HTTP/2 headers. The vulnerability allows remote attackers to crash or make the server unresponsive by sending malicious header data through HTTP/2 connections.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2.2.3CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed H2O versionRun `h2o --version` or `h2o -v` to retrieve the version number of the H2O web server binary installed on the systemAffected if The version displayed is 2.2.3 or any earlier version (for example, 2.2.0, 2.1.0, etc.)
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Locate H2O configuration fileFind the H2O configuration file (commonly at /etc/h2o/h2o.conf or within the /etc/h2o/ directory) that controls the server's runtime behaviorAffected if A configuration file exists and is in active use by the H2O instance
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Verify if HTTP/2 is enabledInspect the configuration file for 'http2:' directives or HTTP/2-related settings. Search for lines beginning with 'http2:' or containing 'http2' to determine if the HTTP/2 protocol is explicitly configuredAffected if The http2: directive is present and set to a value that enables HTTP/2 (such as 'http2: ON' or simply 'http2:' without a disable flag)
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Check for HTTP/2 listener bindingsReview configuration sections that define listen sockets (typically 'listen:' blocks) and verify whether any of them have the http2: directive attached, indicating those listeners accept HTTP/2 connectionsAffected if At least one listen directive includes http2: configuration, meaning the server accepts HTTP/2 connections
You are affected if H2O version is 2.2.3 or earlier AND HTTP/2 is enabled in your configuration, as the denial-of-service only triggers through malicious HTTP/2 header traffic.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataUpgrade H2O to a version newer than 2.2.3 (patched release). As a temporary workaround, consider disabling HTTP/2 or implementing strict header validation/limits at a reverse proxy if upgrade is not immediately feasible.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-10908 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2017-10908 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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