CVE-2021-25291 [High] | Out-of-bounds Read in Pillow

CVE-2021-25291 is rated Moderate Risk (55.2/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.43%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.54%	1.43%	+0.89%
2	2025-03-30	1.82%	0.54%	-1.29%
3	2025-03-29	—	1.82%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.54%

1.43%

+0.89%

2025-03-30

1.82%

0.54%

-1.29%

2025-03-29

—

1.82%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	3.6	[email protected]
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:N/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

3.6

[email protected]

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2021-25291

vendor	priority	summary	link
`alpine`	high	CVE-2021-25291: 1 source package rows (py3-pillow); 8 state rows across 8 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community, edge-main); fixed 8, open 0.	https://security.alpinelinux.org/vuln/CVE-2021-25291
`debian`	not yet assigned	CVE-2021-25291 not yet assigned priority: Debian including 1 source packages (pillow), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2021-25291
`gentoo`	normal	CVE-2021-25291: 1 GLSA(s) (202107-33), 1 atom(s) (dev-python/pillow); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-25291
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2021-25291
`suse`	high	CVE-2021-25291 severity important: SUSE including 20 source package names (python-Pillow, python3-CairoSVG-2.5.1-lp152.2.3.1, …), 25 product×package rows across 10 product lines (HPE Helion OpenStack 8, SUSE Linux Enterprise Module for Python 3 15 SP6, … (10 product lines)): Fixed 19, Known Not Affected 6.	https://www.suse.com/security/cve/CVE-2021-25291/
`ubuntu`	medium	CVE-2021-25291 medium priority: Ubuntu including 3 source packages (pillow, pillow-python2, python-imaging), 48 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 28, not-affected 13, needs-triage 3, released 3, ignored 1.	https://ubuntu.com/security/CVE-2021-25291

Affected software / configurations for CVE-2021-25291

Vendor	Product	Version	Raw CPE
python	pillow	< 8.1.1	cpe:2.3:a:python:pillow::::::::

References for CVE-2021-25291

URL	Tags
https://pillow.readthedocs.io/en/stable/releasenotes/8.1.1.html	Release Notes Vendor Advisory
https://security.gentoo.org/glsa/202107-33	Third Party Advisory

URL

CVE-2021-25291

Exploit prediction scoring system (EPSS) score for CVE-2021-25291

Common vulnerability scoring system (CVSS) metrics for CVE-2021-25291

Weakness enumeration for CVE-2021-25291

GitHub Security Advisory for CVE-2021-25291

OS Trackers for CVE-2021-25291

Affected software / configurations for CVE-2021-25291

References for CVE-2021-25291