Debian LinuxOperating system · Debian
CVE-2020-36476
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 Mbed TLS before 2.24.0 (and before 2.16.8 LTS and before 2.7.17 LTS). There is missing zeroization of plaintext buffers in mbedtls_ssl_read to erase unused application data from 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 confidenceMbed TLS fails to zeroize plaintext buffers in mbedtls_ssl_read, leaving unused application data in memory after SSL reads complete. This could allow attackers with memory access to recover sensitive data from the process heap.
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
Debian LinuxOperating system
= 9.0= 10.0< 2.7.17>= 2.8.0, < 2.16.8>= 2.17.0, < 2.24.0CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checksWork through these to decide whether this CVE applies to you.
-
Identify Mbed TLS installationRun `dpkg -l | grep mbed` on Debian systems, or check library files like `libmbedtls.so` using `ldconfig -p | grep mbed`. For source builds, check the version header file or the mbedtls version string.Affected if Mbed TLS is present on the system
-
Determine installed Mbed TLS versionRun `dpkg -l libmbedtls*` on Debian, or use `openssl version -a` if linked, or examine the library file directly with `strings libmbedtls.so | grep -i mbedtls | head`. The version may also appear in application logs at startup.Affected if The version cannot be determined or is within < 2.7.17, >= 2.8.0 < 2.16.8, or >= 2.17.0 < 2.24.0
-
Verify SSL read functionality is in useReview application configuration to confirm it establishes SSL/TLS connections using Mbed TLS. Check for configurations using mbedtls_ssl_read calls, or monitor network connections with SSL/TLS enabled.Affected if The application performs SSL/TLS read operations using the affected Mbed TLS library
-
Compare version to affected rangesIf version is identified, compare it to the affected ranges: versions less than 2.7.17, versions 2.8.0 through 2.16.7, or versions 2.17.0 through 2.23.0 are vulnerable.Affected if The installed version falls within any of these ranges: < 2.7.17, >= 2.8.0 and < 2.16.8, >= 2.17.0 and < 2.24.0
You are affected if Mbed TLS is installed with a version less than 2.7.17, between 2.8.0 and 2.16.7, or between 2.17.0 and 2.23.0, and your application performs SSL/TLS read operations using that library.
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.
dbcve · scoped2.7.172.16.82.24.0
Upgrade Mbed TLS to version 2.24.0, 2.16.8 LTS, or 2.7.17 LTS or later to receive the patch that properly zeroizes buffers after SSL reads.
Mbed TLS 2.24.0 or later (or LTS versions 2.16.8 / 2.7.17)
- Identify the current Mbed TLS version in use by checking library files or package manager
- For Debian 9.0/10.0: Run 'apt-get update && apt-get upgrade libmbedtls2' or 'apt-get update && apt-get upgrade libmbedtls-dev' to install the patched packages
- For Mbed TLS from source: Download Mbed TLS 2.24.0 or later (or LTS versions 2.16.8+ / 2.7.17+) from the official repository
- Compile and install the new version following the build instructions in the README
- Verify the new version is active: check mbedtls version via 'grep -r version' or the library binary
- Restart any services using Mbed TLS to ensure the patched library is loaded
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,752.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-36476 — 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-2020-36476 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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
- No spam, self-promotion, credentials, or personal data