Debian LinuxOperating system · Debian
CVE-2020-11728
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 DAViCal Andrew's Web Libraries (AWL) through 0.60. Session management does not use a sufficiently hard-to-guess session key. Anyone who can guess the microsecond time (and the incrementing session_id) can impersonate a session.
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 confidenceThe session management in DAViCal AWL through version 0.60 uses predictable session keys based on microsecond timestamps combined with an incrementing session_id counter. Attackers who can determine the approximate time and predict the session_id sequence can calculate valid session identifiers and impersonate legitimate users.
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
= 8.0= 9.0= 10.0<= 0.60CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify DAViCal AWL installation and versionLocate the AWL library files and check the version number against the affected range (version 0.60 and below). Common methods include: checking a VERSION file, running a package manager query (dpkg/apt for Debian), or inspecting the main AWL library file for a version constant.Affected if The installed version is 0.60 or lower, or the version cannot be determined but is suspected to be old.
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Confirm session management is in useDetermine whether the DAViCal AWL installation has session management functionality enabled or active. This may involve checking if session-related code paths are being executed, or reviewing the application configuration to see if user authentication sessions are configured.Affected if Session management is active and handling user authentication sessions.
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Inspect session identifier generation mechanismExamine the code responsible for generating session IDs. Look for implementation patterns that combine time-based values (such as microsecond timestamps) with sequential counters. The specific files and functions will vary by installation, but the pattern to identify is session ID generation based on predictable timing and incrementing values rather than cryptographic randomness.Affected if The session ID generation uses timestamps combined with incrementing counters, rather than cryptographically random values.
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Review session configuration for predictabilityCheck the session configuration files or PHP session settings to see how session IDs are being created and stored. Look for configuration that does not specify cryptographically secure random session token generation.Affected if The session configuration does not use cryptographically secure random session ID generation (such as random_bytes() or equivalent).
You are affected if DAViCal AWL version 0.60 or lower is installed, session management is active, and the session ID generation relies on predictable microsecond timestamps combined with incrementing counters instead of cryptographic randomness.
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 to a patched version of AWL that implements cryptographically secure random session ID generation, or modify the session management code to use cryptographically strong random session tokens (e.g., random_bytes() in PHP).
Fix this in Debian Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-11728 — 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-2020-11728 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
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