How severe is CVE-2026-28231?

CVE-2026-28231 has a CVSS 3.x base score of 9.1, 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 none, and availability high.

Is CVE-2026-28231 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28231?

CVE-2026-28231 affects Bigcat88 Pillow-heif. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28231?

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.

Does CVE-2026-28231 have an EU (EUVD) identifier?

Yes. CVE-2026-28231 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9061.

When was CVE-2026-28231 published?

CVE-2026-28231 was published on 2026-02-27 and last updated on 2026-06-17.

CVE-2026-28231

CVE-2026-28231 is a critical-severity vulnerability in Bigcat88 Pillow-heif with a CVSS 3.x base score of 9.1. 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-125.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 5.5
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-9061
Weakness: CWE-125
Affected product: Bigcat88 Pillow-heif
Published: 2026-02-27
Last modified: 2026-06-17

Description

pillow_heif is a Python library for working with HEIF images and plugin for Pillow. Prior to version 1.3.0, an integer overflow in the encode path buffer validation of `_pillow_heif.c` allows an attacker to bypass bounds checks by providing large image dimensions, resulting in a heap out-of-bounds read. This can lead to information disclosure (server heap memory leaking into encoded images) or denial of service (process crash). No special configuration is required — this triggers under default settings. Version 1.3.0 fixes the issue.

Frequently asked questions

What is CVE-2026-28231?: pillow_heif is a Python library for working with HEIF images and plugin for Pillow. Prior to version 1.3.0, an integer overflow in the encode path buffer validation of `_pillow_heif.c` allows an attacker to bypass bounds checks by providing large image dimensions, resulting in a heap out-of-bounds read. This can lead to information disclosure (server heap memory leaking into encoded images) or denial of service (process crash). No special configuration is required — this triggers under default settings. Version 1.3.0 fixes the issue.
How severe is CVE-2026-28231?: CVE-2026-28231 has a CVSS 3.x base score of 9.1, 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 none, and availability high.
Is CVE-2026-28231 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28231?: CVE-2026-28231 affects Bigcat88 Pillow-heif. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28231?: 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.
Does CVE-2026-28231 have an EU (EUVD) identifier?: Yes. CVE-2026-28231 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9061.
When was CVE-2026-28231 published?: CVE-2026-28231 was published on 2026-02-27 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:bigcat88:pillow-heif:*:*:*:*:*:python:*:*

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