CVE-2009-4020

CVE-2009-4020 is a high-severity vulnerability in Linux Linux Kernel with a CVSS 2.0 base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.

Key facts

• Severity: High (CVSS 2.0 base score 7.8)
• EPSS exploit prediction: 5% (91st percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-119
• Affected product: Linux Linux Kernel
• Published: 2009-12-04
• Last modified: 2026-06-16

Description

Stack-based buffer overflow in the hfs subsystem in the Linux kernel 2.6.32 allows remote attackers to have an unspecified impact via a crafted Hierarchical File System (HFS) filesystem, related to the hfs_readdir function in fs/hfs/dir.c.

Frequently asked questions

What is CVE-2009-4020?

Stack-based buffer overflow in the hfs subsystem in the Linux kernel 2.6.32 allows remote attackers to have an unspecified impact via a crafted Hierarchical File System (HFS) filesystem, related to the hfs_readdir function in fs/hfs/dir.c.

How severe is CVE-2009-4020?

CVE-2009-4020 has a CVSS 2.0 base score of 7.8, rated high severity.

Is CVE-2009-4020 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2009-4020?

CVE-2009-4020 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2009-4020?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2009-4020 published?

CVE-2009-4020 was published on 2009-12-04 and last updated on 2026-06-16.

References

• http://lists.opensuse.org/opensuse-security-announce/2010-01/msg00005.html
• http://lists.opensuse.org/opensuse-security-announce/2010-03/msg00007.html
• http://marc.info/?l=linux-mm-commits&m=125987755823047&w=2
• http://secunia.com/advisories/38276
• http://secunia.com/advisories/39742
• http://support.avaya.com/css/P8/documents/100073666
• http://userweb.kernel.org/~akpm/mmotm/broken-out/hfs-fix-a-potential-buffer-overflow.patch
• http://www.debian.org/security/2010/dsa-2005
• http://www.novell.com/linux/security/advisories/2010_23_kernel.html
• http://www.openwall.com/lists/oss-security/2009/12/04/1
• https://bugzilla.redhat.com/show_bug.cgi?id=540736
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10091
• https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6750
• https://rhn.redhat.com/errata/RHSA-2010-0046.html
• https://rhn.redhat.com/errata/RHSA-2010-0095.html

Affected products (1)

• cpe:2.3:o:linux:linux_kernel:2.6.32:*:*:*:*:*:*:*

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