CVE-2023-30311
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 · uneditedAn issue discovered in H3C Magic R365 and H3C Magic R100 routers allows attackers to hijack TCP sessions which could lead to a denial of service.
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 confidenceThis vulnerability in H3C Magic R365 and R100 routers allows attackers to hijack TCP sessions, likely through TCP sequence number prediction or injection attacks, enabling disruption of existing connections and potentially causing denial of service by intercepting or terminating legitimate traffic.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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:3.1/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 router modelCheck the device label or access the router admin interface (typically at 192.168.1.1 or 192.168.0.1) to confirm the exact model number is H3C Magic R365 or R100Affected if The device is an H3C Magic R365 or R100 router
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Check firmware versionAccess router admin interface, look for firmware/version information in System Settings, Status, or About page. Alternatively, check the firmware file name if you have direct access to firmware binariesAffected if Firmware version is older than the vendor patched version (no specific patched version provided in CVE data)
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Verify TCP session exposureCheck if remote management, WAN access, or exposed services allow TCP connections from untrusted networks. Review port forwards, UPnP settings, and firewall rulesAffected if Router has TCP services exposed to WAN or untrusted networks (e.g., remote management enabled on WAN interface)
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Monitor for TCP anomaliesUse network capture tools (tcpdump, Wireshark) on LAN/WAN interfaces to observe TCP sequence numbers and connection patterns for predictability or injection attemptsAffected if TCP sessions show suspicious patterns such as predictable sequence numbers or unexpected packets in established connections
User is affected if they operate an H3C Magic R365 or R100 router with exposed TCP services and firmware versions prior to vendor patches.
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 dataApply vendor firmware updates when available; if no patch exists, consider network segmentation to limit router exposure and monitor for anomalous TCP session behavior.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2023-30311 — 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-2023-30311 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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- 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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