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Fencer Vulns
high 7.5

CVE-2021-28676 json

Potential infinite loop in Pillow

published 2021-06-02 5 y ago modified 2026-09-08 2 mo ago also BIT-pillow-2021-28676 , EUVD-2021-0183 , GHSA-7r7m-5h27-29hp , PYSEC-2021-92

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.5%
EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits
0
none known

Summary

An issue was discovered in Pillow before 8.2.0. For FLI data, FliDecode did not properly check that the block advance was non-zero, potentially leading to an infinite loop on load.

Patch / fix

  • pypi pillow 8.2.0
  • bitnami pillow 8.2.0
  • python pillow 8.2.0
  • pillow Debian 14, Debian 13, Debian 12 8.1.2+dfsg-0.2

debian advisories DEBIAN-CVE-2021-28676

  • pillow Ubuntu 18.04 LTS 5.1.0-1ubuntu0.6
  • pillow Ubuntu 20.04 LTS 7.0.0-4ubuntu0.4
  • pillow Ubuntu Pro 14.04 LTS 2.3.0-1ubuntu3.4+esm5
  • pillow Ubuntu Pro 16.04 LTS 3.1.2-0ubuntu1.6+esm3

ubuntu advisories UBUNTU-CVE-2021-28676

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-pillow RHEL 8 5.1.1-16.el8
  • python3-pillow RHEL 8 5.1.1-16.el8

red hat advisories RHSA-2021:4149

  • python-Pillow openSUSE Leap 15.5 7.2.0-150300.3.12.1
  • python-Pillow OpenStack Cloud 7 2.8.1-4.22.1
  • python-Pillow OpenStack Cloud Crowbar 8, OpenStack Cloud 8, HPE Helion OpenStack 8 4.2.1-3.14.1
  • python-Pillow OpenStack Cloud Crowbar 9, OpenStack Cloud 9 5.2.0-3.8.1

suse advisories SUSE-SU-2024:1607-1SUSE-SU-2021:1940-1SUSE-SU-2021:1939-1SUSE-SU-2021:1938-1

  • python3-pillow AlmaLinux 8 5.1.1-16.el8

almalinux advisories ALSA-2021:4149

  • python-pillow Rocky Linux 8 5.1.1-16.el8

rocky linux advisories RLSA-2021:4149

  • py3-pillow Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 8.2.0-r0

alpine advisories ALPINE-CVE-2021-28676

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-28676 updated cvss 7.5

python-pillow: Infinite loop in FLI image reader

  • Red Hat Enterprise Linux 7 python-pillow, python-pillow-qt, python-pillow-tk, python-pillow-sane
    affected: workaround, no fix planned “To mitigate this feature on Red Hat Quay, keep the invoice generation feature disabled, as it is by default.”
  • Red Hat Quay 3 quay/quay-rhel8
    affected: workaround, no fix available “To mitigate this feature on Red Hat Quay, keep the invoice generation feature disabled, as it is by default.”
  • Red Hat Enterprise Linux AppStream (v. 8) python-pillow 5.1.1-16.el8, python3-pillow 5.1.1-16.el8
    fixed: vendor fix “To mitigate this feature on Red Hat Quay, keep the invoice generation feature disabled, as it is by default.” RHSA-2021:4149

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.50% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi pillow
<8.2.0
8.2.0
bitnami pillow
<8.2.0
8.2.0

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.