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OpenSSLFramework / library

CVE-2009-4355

MEDIUM · 5.0 CVSS v2.0 Published 2010-01-14
Fix available
A fix is available. Upgrade to after 0.9.8l or later.
See remediation →
59/100
Remediation priority · Elevated
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
Memory leak in the zlib_stateful_finish function in crypto/comp/c_zlib.c in OpenSSL 0.9.8l and earlier and 1.0.0 Beta through Beta 4 allows remote attackers to cause a denial of service (memory consumption) via vectors that trigger incorrect calls to the CRYPTO_cleanup_all_ex_data function, as demonstrated by use of SSLv3 and PHP with the Apache HTTP Server, a related issue to CVE-2008-1678.

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

Memory leak in OpenSSL's zlib_stateful_finish function (crypto/comp/c_zlib.c) allows remote attackers to cause denial of service through memory consumption. The vulnerability is triggered when incorrect calls to CRYPTO_cleanup_all_ex_data occur during SSLv3 connections using zlib compression, as demonstrated with PHP and Apache HTTP Server.

MitigationUpgrade OpenSSL to version 0.9.8m or later (or 1.0.0 Beta 5+). If immediate patching is not possible, consider disabling SSLv3 or zlib compression in SSL/TLS configurations to reduce attack surface.

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
OpenSSLFramework / library
Affected:<= 0.9.8l= 0.9.1c= 0.9.2b= 0.9.3= 0.9.3a= 0.9.4= 0.9.5= 0.9.5a= 0.9.6= 0.9.6a= 0.9.6b= 0.9.6c
OpenSSLFramework / library
Affected:= 0.9.6-15= 0.9.6b-3= 0.9.7a-2

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
Authentication
None
Confidentiality
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

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 installed OpenSSL version
    Run 'openssl version' or check package manager (rpm -qa | grep openssl, dpkg -l | grep openssl)
    Affected if Installed version matches any of the affected versions: 0.9.1c, 0.9.2b, 0.9.3, 0.9.3a, 0.9.4, 0.9.5, 0.9.5a, 0.9.6, 0.9.6a, 0.9.6b, 0.9.6c, 0.9.6-15 (RedHat), 0.9.6b-3 (RedHat), 0.9.7a-2 (RedHat), or any version 0.9.8 through 0.9.8l
  2. Verify SSLv3 protocol is enabled
    Check SSL/TLS configuration files for SSLv3 enablement, or test with 'openssl s_client -ssl3' to see if connections succeed
    Affected if SSLv3 is enabled and accepted by the server/service
  3. Confirm zlib compression is in use for SSL/TLS
    Review application configurations (Apache httpd.conf, PHP openssl config) for SSLCompression directive set to on, or check if zlib is linked into the OpenSSL library
    Affected if Zlib compression for SSL/TLS is enabled or the OpenSSL library was compiled with zlib support and is actively used

Environment is affected if running a vulnerable OpenSSL version (0.9.8l or earlier, or the specific RedHat versions listed) AND SSLv3 is enabled AND zlib compression is being used for SSL/TLS connections.

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.

From vendor data
Upgrade available Upgrade to a release after 0.9.8l
Interim mitigation

Upgrade OpenSSL to version 0.9.8m or later (or 1.0.0 Beta 5+). If immediate patching is not possible, consider disabling SSLv3 or zlib compression in SSL/TLS configurations to reduce attack surface.

Fix this in OpenSSL 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-2009-4355 in production — separate from our analysis above.

No notes yet

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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