How severe is CVE-2016-4009?

CVE-2016-4009 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-4009 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-4009?

CVE-2016-4009 affects Python Pillow. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-4009?

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

When was CVE-2016-4009 published?

CVE-2016-4009 was published on 2016-04-13 and last updated on 2026-06-17.

CVE-2016-4009

CVE-2016-4009 is a critical-severity vulnerability in Python Pillow with a CVSS 3.x base score of 9.8. 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: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 8% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Python Pillow
Published: 2016-04-13
Last modified: 2026-06-17

Description

Integer overflow in the ImagingResampleHorizontal function in libImaging/Resample.c in Pillow before 3.1.1 allows remote attackers to have unspecified impact via negative values of the new size, which triggers a heap-based buffer overflow.

Frequently asked questions

What is CVE-2016-4009?: Integer overflow in the ImagingResampleHorizontal function in libImaging/Resample.c in Pillow before 3.1.1 allows remote attackers to have unspecified impact via negative values of the new size, which triggers a heap-based buffer overflow.
How severe is CVE-2016-4009?: CVE-2016-4009 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-4009 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-4009?: CVE-2016-4009 affects Python Pillow. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-4009?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2016-4009 published?: CVE-2016-4009 was published on 2016-04-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:python:pillow:*:*:*:*:*:*:*:*

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