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Edk2Application · Tianocore

CVE-2023-45237

HIGH · 7.5 CVSS v3.1 Published 2024-01-16
Fix available
A fix is available. Upgrade to after 202311 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
EDK2's Network Package is susceptible to a predictable TCP Initial Sequence Number. This vulnerability can be exploited by an attacker to gain unauthorized access and potentially lead to a loss of Confidentiality.

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 · high confidence

EDK2's Network Package uses a predictable TCP Initial Sequence Number (ISN) generation mechanism, allowing remote attackers to potentially hijack TCP sessions or perform man-in-the-middle attacks by guessing or calculating future sequence numbers. The vulnerability stems from insufficient randomness in the ISN generation algorithm within the UEFI network stack.

MitigationImplement a cryptographically secure random number generator for TCP ISN creation to ensure unpredictability, and update EDK2 to a version with this fix applied.

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
Edk2Application
Affected:<= 202311

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify if the system uses EDK2-based UEFI firmware
    Check system firmware information using tools like dmidecode -s bios-version, uefiinfo, or inspect the firmware vendor/string in system information utilities. Look for references to Tianocore, EDK2, or EDK II in the firmware details.
    Affected if The system firmware is based on Tianocore EDK2 and the version displays 202311 or earlier, or the version cannot be determined but EDK2 is identified as the firmware foundation
  2. Determine the EDK2 package version
    If you have access to the EDK2 source code or build environment, inspect the version tag or build metadata in the SourceLevelDebugPkg or BaseTools version files. Check any version indicators in the UEFI firmware update package if available.
    Affected if The EDK2 version is 202311 or earlier, or the version cannot be verified but the firmware is confirmed as EDK2-based
  3. Verify if the UEFI network stack is enabled
    Check system configuration for UEFI network boot, PXE boot, iPXE, or UEFI network services. On systems with UEFI setup screens, look for Network Stack, PXE Boot, or Network Configuration options. In Linux, check /sys/firmware/efi for network-related boot options or inspect boot configurations.
    Affected if UEFI network functionality such as network boot, PXE, or UEFI network services are enabled or configured on the system
  4. Confirm network package usage in custom EDK2 builds
    If you build custom EDK2 firmware, inspect the DSC file for the presence of NetworkPkg and verify whether TCP/IP stack components are included in the build configuration.
    Affected if NetworkPkg with TCP/IP stack is included in a custom EDK2 build version 202311 or earlier

The system is likely affected if it runs EDK2 firmware version 202311 or earlier with the UEFI network stack or network boot functionality enabled.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 202311
Interim mitigation

Implement a cryptographically secure random number generator for TCP ISN creation to ensure unpredictability, and update EDK2 to a version with this fix applied.

Recommended fix High confidence

EDK2 version > 202311 (e.g., 2024.01 or later)

  1. 1. Identify all systems, devices, or firmware implementations that use EDK2 Network Package version 202311 or earlier
  2. 2. Check with your hardware or firmware vendor for available updates that address CVE-2023-45237
  3. 3. Apply the vendor-provided firmware update that includes the patched EDK2 version
  4. 4. After applying the update, verify that the EDK2 Network Package has been updated to a version greater than 202311
  5. 5. Test the network functionality to ensure the update does not break existing operations
Caveat Firmware updates may require system downtime and should be tested in a staging environment first; some legacy network configurations may be affected by changes to TCP ISN generation

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Edk2 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-45237 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data