high CVSS 7.5

CVE-2026-55380·Python vulnerability

Pillow is a Python imaging library. Prior to 12.3.0, PIL/GdImageFile.py GdImageFile._open() read image dimensions from the GD 2.x header and stored them in self._size without calling Image._decompression_bomb_check(), allowing a crafted .gd file to trigger excessive C-heap allocation when loaded. This issue is fixed in version 12.3.0.

Severity
high
Software
Python
Fixed in
12.3.0
Published
2026-07-06

Affected versions

Until: 12.3.0

Fixed in: 12.3.0

How to fix this CVE

Update the Pillow library to version 12.3.0 or later to remediate this decompression bomb vulnerability in GD image file handling. The fix ensures that image dimension validation is properly enforced before memory allocation occurs, preventing maliciously crafted .gd files from causing excessive heap memory consumption. If you use Pillow for image processing, prioritize this update to eliminate the denial-of-service risk.

sudo dnf update python3-pillow

Defensia detects this vulnerability

How to check if you are affected

  1. Check installed Pillow version: python3 -c "import PIL; print(PIL.__version__)"
  2. Verify if your application processes .gd format images: grep -r '\.gd' /path/to/app/config /path/to/app/uploads 2>/dev/null || echo 'No .gd files found in application directories'
  3. Search system logs for memory exhaustion events: grep -i 'out of memory\|oom-killer\|heap' /var/log/syslog /var/log/messages 2>/dev/null | head -20
  4. Confirm the patch: python3 -c "import PIL; print('Patched' if PIL.__version__ >= '12.3.0' else 'Vulnerable')"

FAQ

What is CVE-2026-55380?

CVE-2026-55380 is a denial-of-service vulnerability in Pillow's GD image file parser where crafted .gd files can trigger excessive C-heap memory allocation without proper validation, potentially crashing applications that process untrusted image files.

Is CVE-2026-55380 being actively exploited?

No, CVE-2026-55380 is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available.

What versions of Python are affected by CVE-2026-55380?

The vulnerability affects Pillow versions prior to 12.3.0. Any Python installation using an older version of the Pillow imaging library is at risk.

How do I check if my server is vulnerable to CVE-2026-55380?

Run: python3 -c "import PIL; print(PIL.__version__)" and verify the version is 12.3.0 or later. If it's earlier, your system is vulnerable.

Does Defensia detect CVE-2026-55380?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Pillow is installed on a monitored server, CVE-2026-55380 will appear in your dashboard with remediation steps.

Related Python CVEs

CVE-2026-25632CVSS 10EPyT-Flow is a Python package designed for the easy generation of hydraulic and water quality scenario data of water distribution networks. Prior to 0.16.1, EPyT-Flow’s REST API parses attacker-controlled JSON request bodies using a custom deserializer (my_load_from_json) that supports a type field. When type is present, the deserializer dynamically imports an attacker-specified module/class and instantiates it with attacker-supplied arguments. This allows invoking dangerous classes such as subprocess.Popen, which can lead to OS command execution during JSON parsing. This also affects the loading of JSON files. This vulnerability is fixed in 0.16.1.
CVE-2026-33054CVSS 10Mesop is a Python-based UI framework that allows users to build web applications. Versions 1.2.2 and below contain a Path Traversal vulnerability that allows any user supplying an untrusted state_token through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation. This vulnerability heavily exposes systems hosted utilizing FileStateSessionBackend. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds. This issue has been fixed in version 1.2.3.
CVE-2026-34938CVSS 10PraisonAI is a multi-agent teams system. Prior to version 1.5.90, execute_code() in praisonai-agents runs attacker-controlled Python inside a three-layer sandbox that can be fully bypassed by passing a str subclass with an overridden startswith() method to the _safe_getattr wrapper, achieving arbitrary OS command execution on the host. This issue has been patched in version 1.5.90.
CVE-2026-28505CVSS 10Tautulli is a Python based monitoring and tracking tool for Plex Media Server. Prior to version 2.17.0, the str_eval() function in notification_handler.py implements a sandboxed eval() for notification text templates. The sandbox attempts to restrict callable names by inspecting code.co_names of the compiled code object. However, co_names only contains names from the outer code object. When a lambda expression is used, it creates a nested code object whose attribute accesses are stored in code.co_consts, NOT in code.co_names. The sandbox never inspects nested code objects. This issue has been patched in version 2.17.0.
CVE-2026-25115CVSS 9.9n8n is an open source workflow automation platform. Prior to version 2.4.8, a vulnerability in the Python Code node allows authenticated users to break out of the Python sandbox environment and execute code outside the intended security boundary. This issue has been patched in version 2.4.8.

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2026-55380. Free for 1 server.

Get started free