CVE-2009-4355

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

9.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2010-01-14 19:30 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-16 23:13 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 9.2% in the next 30 days (EPSS).
• Severity: 5.0 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2010-01-14 19:30 UTC

Last modified

2026-06-16 23:13 UTC

Exploit probability

9.2% · EPSS, next 30 days

Weakness

CWE-399

Record status

Modified

Affected

• OpenSSL ≤ 0.9.8l
• OpenSSL 0.9.1c
• OpenSSL 0.9.2b
• OpenSSL 0.9.3
• OpenSSL 0.9.3a
• OpenSSL 0.9.4
• OpenSSL 0.9.5
• OpenSSL 0.9.5a

Attack profile CVSS 2.0 · 5.0

Attack vector

Network

Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Partial

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

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