VulnerabilityPublished 29 Oct 2026

CVE-2026-114501: Arrow export leaks stale heap memory when PILLOW_ALIGNMENT > 1

Affects pillowSource GCVE Database

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Authoritative record:CVE-2026-114501· Medium 6.3

Not known to be exploited · CVSS 6.3 Medium : upgrade to 13.0.0 when convenient.

Data as of 29 Oct 2026, 13:06 UTC

CVSS 4.0 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 13.0.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 21 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade pillow to 13.0.0.

Patches and advisories

github.com/python-pillow/Pillow/commit/19f64946eb247b973dd4560be7dea3bf979d2e6a (opens in a new tab)

Affected software

Product	Affected	Fixed in
Bitnamipillow`pkg:bitnami/pillow`Other threats	Affected >=11.2.1 <13.0.0	Fixed in 13.0.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Pillow to version 13.0.0 or later, where this vulnerability is fixed. The patch is available and should be applied to prevent memory disclosure via Arrow exports when PILLOW_ALIGNMENT is greater than 1.

Description

Pillow versions from 11.2.1 up to but not including 13.0.0 have a vulnerability in the Arrow export feature where stale heap memory can be leaked due to incorrect handling of image row alignment. This can cause uninitialized or previously freed memory to be included in the exported Arrow buffer, potentially disclosing sensitive data between users. The issue is fixed in version 13.0.0.

Impact

Applications that use Pillow with configured alignment and export images to Arrow format may inadvertently expose sensitive memory contents, including pixels from other users or stale heap data. This can lead to information disclosure between users of the application. No known exploits in the wild have been reported.

Summary

The Pillow Python imaging library's Arrow export functionality, in versions 11.2.1 through 12.x, incorrectly assumes image rows are tightly contiguous. When PILLOW_ALIGNMENT is greater than 1, this assumption fails, causing the export to include uninitialized padding, bytes before the first row, or stale heap memory from previously freed images. This memory disclosure vulnerability can lead to leakage of one user's pixel data or other process memory to another user. The vulnerability is resolved in Pillow 13.0.0.

References

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