Summary
Workarounds
An issue was discovered in Pillow before 6.2.0. When reading specially crafted invalid image files, the library can either allocate very large amounts of memory or take an extremely long period of time to process the image.
References
https://nvd.nist.gov/vuln/detail/CVE-2021-27921
For more information
If you have any questions or comments about this advisory:
- Open an issue in example link to repo
- Email us at example email address
Impact
Pillow before 8.1.1 allows attackers to cause a denial of service (memory consumption) because the reported size of a contained image is not properly checked for a BLP container, and thus an attempted memory allocation can be very large.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
GHSA-JGPV-4H4C-XHW3 has a CVSS score of 7.5 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (8.1.2); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
An issue was discovered in Pillow before 6.2.0. When reading specially crafted invalid image files, the library can either allocate very large amounts of memory or take an extremely long period of time to process the image.
Frequently Asked Questions
- What is GHSA-JGPV-4H4C-XHW3? GHSA-JGPV-4H4C-XHW3 is a medium-severity uncontrolled resource consumption vulnerability in pillow (pip), affecting versions < 8.1.1. It is fixed in 8.1.2. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- How severe is GHSA-JGPV-4H4C-XHW3? GHSA-JGPV-4H4C-XHW3 has a CVSS score of 7.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of pillow are affected by GHSA-JGPV-4H4C-XHW3? pillow (pip) versions < 8.1.1 is affected.
- Is there a fix for GHSA-JGPV-4H4C-XHW3? Yes. GHSA-JGPV-4H4C-XHW3 is fixed in 8.1.2. Upgrade to this version or later.
- Is GHSA-JGPV-4H4C-XHW3 exploitable, and should I be worried? Whether GHSA-JGPV-4H4C-XHW3 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-JGPV-4H4C-XHW3 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-JGPV-4H4C-XHW3? Upgrade
pillowto 8.1.2 or later.