Pillow up to 12.x Spider Image Plugin SpiderImagePlugin.py SpiderImageFile.seek allocation of resources

Summaryinfo

A vulnerability marked as problematic has been reported in Pillow up to 12.x. This affects the function SpiderImageFile.seek of the file src/PIL/SpiderImagePlugin.py of the component Spider Image Plugin. The manipulation leads to allocation of resources. This vulnerability is traded as CVE-2026-96637. It is possible to initiate the attack remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Pillow up to 12.x. This issue affects the function SpiderImageFile.seek of the file src/PIL/SpiderImagePlugin.py of the component Spider Image Plugin. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. The summary by CVE is:

Pillow is a Python imaging library. Prior to 13.0.0, SpiderImageFile.seek() in src/PIL/SpiderImagePlugin.py reparses a later SPIDER stack frame and replaces self._size without rerunning Image._decompression_bomb_check(). A tiny file can use a safe first frame to pass Image.open() and then declare very large dimensions in a later mode F frame. Loading that frame allocates approximately four bytes per attacker-declared pixel and can consume multiple gigabytes of memory. This issue is fixed in version 13.0.0.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-96637 since 09/23/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 370273 (Linux Distros Unpatched Vulnerability : CVE-2026-96637), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 13.0.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (370273). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Pillow

Version

• 12.x

License

• open-source

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion