CVE-2018-18558
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 was discovered in Espressif ESP-IDF 2.x and 3.x before 3.0.6 and 3.1.x before 3.1.1. Insufficient validation of input data in the 2nd stage bootloader allows a physically proximate attacker to bypass secure boot checks and execute arbitrary code, by crafting an application binary that overwrites a bootloader code segment in process_segment in components/bootloader_support/src/esp_image_format.c. The attack is effective when the flash encryption feature is not enabled, or if the attacker finds a different vulnerability that allows them to write this binary to flash memory.
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 confidenceInsufficient validation of input data in the 2nd stage bootloader in ESP-IDF allows a physically proximate attacker to bypass secure boot checks by crafting an application binary that overwrites bootloader code segments in the process_segment function. The attack succeeds when flash encryption is disabled or if an attacker can write a malicious binary to flash memory.
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>= 2.0, < 3.0.6>= 3.1, <= 3.1.1CVSS 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
- Physical
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 the ESP-IDF version in useRun 'idf.py --version' or check the ESP-IDF directory version file to determine the installed version numberAffected if The installed version is >= 2.0 and < 3.0.6, or >= 3.1 and <= 3.1.1
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Verify flash encryption statusCheck the project sdkconfig file (sdkconfig) or run 'idf.py menuconfig' and look under 'Security Features' for flash encryption settings - check if CONFIG_SECURE_FLASH_ENC_ENABLED or similar option is set to 'y' or enabledAffected if Flash encryption is disabled or not configured in the build settings
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Confirm secure boot configurationCheck the sdkconfig file or menuconfig for CONFIG_SECURE_BOOT_ENABLED or 'Secure Boot' option - verify whether secure boot is actually enabled in the deployed firmwareAffected if Secure boot is enabled but flash encryption is disabled (the bypass requires this specific combination)
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Inspect bootloader configurationExamine the compiled bootloader binary or the bootloader configuration in the build directory to determine if custom bootloader code is being used, and check if process_segment function handles input validationAffected if A custom or unmodified bootloader from an affected ESP-IDF version is in use without the patch applied
A system is affected if it uses a vulnerable ESP-IDF version (2.0-3.0.5 or 3.1-3.1.1) with secure boot enabled but flash encryption disabled, allowing an attacker with physical flash access to overwrite bootloader code segments.
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 data3.0.6
Enable flash encryption and upgrade ESP-IDF to version 3.0.6 or later (3.1.x to 3.1.1 or later) to patch the insufficient input validation vulnerability in the bootloader.
- 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-2018-18558 — 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-2018-18558 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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- Version or environment caveats, and links to real fixes
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