Summary
Uncapped length of skin data fields submitted by players
Workarounds
A plugin may check player skins during PlayerLoginEvent and PlayerSkinChangeEvent and ensure that the offending fields are not larger than 32767 bytes.
For more information
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Impact
Some skin data fields (e.g. skinID, geometryName) are not capped in length. These fields are typically saved in the NBT data of a player when the player quits the server, or during an autosave.
This is problematic due to the 32767 byte limit on TAG_Strings. If any of these fields exceeds 32767 bytes, an exception will be thrown during data saving, which will cause the server to crash.
Other fields (such as skinGeometryData) are also uncapped, but those have a much larger 2 GB length limit, so this is not a concern for those, particularly considering the decompressed packet size limit of 2 MB.
GHSA-C6FG-99PR-25M9 has a CVSS score of 7.5 (High). 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 (3.26.5, 4.0.5); 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.
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PM3: 958a9dbf0fe3131ab60319c5a939f5dfbfe5dfbb
PM4: 6492cac5c10f9fa8443ceddd2191a7b65b73f601
Frequently Asked Questions
- What is GHSA-C6FG-99PR-25M9? GHSA-C6FG-99PR-25M9 is a high-severity security vulnerability in pocketmine/pocketmine-mp (composer), affecting versions < 3.26.5. It is fixed in 3.26.5, 4.0.5.
- How severe is GHSA-C6FG-99PR-25M9? GHSA-C6FG-99PR-25M9 has a CVSS score of 7.5 (High). 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 pocketmine/pocketmine-mp are affected by GHSA-C6FG-99PR-25M9? pocketmine/pocketmine-mp (composer) versions < 3.26.5 is affected.
- Is there a fix for GHSA-C6FG-99PR-25M9? Yes. GHSA-C6FG-99PR-25M9 is fixed in 3.26.5, 4.0.5. Upgrade to this version or later.
- Is GHSA-C6FG-99PR-25M9 exploitable, and should I be worried? Whether GHSA-C6FG-99PR-25M9 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-C6FG-99PR-25M9 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-C6FG-99PR-25M9?
- Upgrade
pocketmine/pocketmine-mpto 3.26.5 or later - Upgrade
pocketmine/pocketmine-mpto 4.0.5 or later
- Upgrade