FedoraOperating system · Fedoraproject
CVE-2019-12528
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 Squid before 4.10. It allows a crafted FTP server to trigger disclosure of sensitive information from heap memory, such as information associated with other users' sessions or non-Squid processes.
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 confidenceSquid before version 4.10 contains a heap memory disclosure vulnerability in its FTP protocol handling. When Squid connects to a malicious FTP server that sends specially crafted responses, it can cause Squid to leak sensitive heap memory contents, potentially exposing session data from other users or information from unrelated processes.
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
FedoraOperating system
= 30= 31
Debian LinuxOperating system
= 9.0= 10.0
Ubuntu LinuxOperating system
= 16.04= 18.04= 19.10< 4.10= 15.1CVSS 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
- 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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Determine installed Squid versionRun 'squid -v' or 'squid -V' to display version information, or check the package manager (dpkg -l squid, rpm -qi squid, or dnf list squid)Affected if The displayed version is earlier than 4.10 (for example, 4.9, 4.8, 4.7, 4.0, 3.x)
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Verify FTP gateway support is enabledInspect the Squid configuration file (typically /etc/squid/squid.conf) for lines containing 'ftp' or 'ftp_gateway' or look for any FTP-related access control rulesAffected if FTP protocol support is explicitly configured or enabled in the configuration file
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Check for active FTP proxy port listenerRun 'netstat -tlnp | grep squid' or 'ss -tlnp | grep squid' to see which ports Squid is listening on, and look for port 21 or the configured FTP gateway portAffected if Squid is listening on an FTP-related port, indicating FTP proxy functionality is active
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Confirm FTP methods are allowedReview Squid access control lists (ACLs) in the configuration file for 'ftp' method access, such as 'http_access allow ftp' or similar rulesAffected if ACLs permit FTP traffic or FTP methods are allowed in the access control rules
A system is affected if it runs Squid version earlier than 4.10 AND has FTP proxy functionality enabled or configured in Squid.
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 data4.10
Upgrade Squid to version 4.10 or later to patch this vulnerability. If immediate upgrading is not possible, consider disabling or severely restricting FTP proxy functionality until the upgrade can be performed.
Fix this in Fedora
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA1.0 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-2019-12528 — 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-2019-12528 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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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
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