CVE-2026-55497 Cloudreve: Server crash through image decompression/pixel bomb in thumbnail & avatar decoding (DoS)
An authenticated user can crash the Cloudreve server by uploading small images with large pixel dimensions, causing out-of-memory errors.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-55497?
CVE-2026-55497 is a medium-severity denial of service vulnerability in cloudreve, published on 31 Jul 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Cloudreve is a self-hosted file management and sharing system. Prior to 4.17.0, the built-in thumbnail and avatar image decoders limit compressed file size but do not limit decoded pixel dimensions, allowing an authenticated user to submit a small PNG, JPEG, or GIF that triggers an unbounded allocation and terminates the Cloudreve process through fatal out-of-memory behavior. This issue is fixed in version 4.17.0.
Which versions are affected by CVE-2026-55497?
7 open source packages ship an affected version, including github.com/cloudreve/Cloudreve/v3, github.com/cloudreve/Cloudreve and github.com/cloudreve/Cloudreve/v4.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cloudreve/Cloudreve/v3 Go | All versions | None |
github.com/cloudreve/Cloudreve/v3 Go | All versions to 3.0.0-20250225100611-da4e44b77af4 | None |
github.com/cloudreve/Cloudreve/v3 Go | All versions to 3.0.0-20250225100611-da4e44b77af4 | None |
github.com/cloudreve/Cloudreve Go | All versions | None |
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260613024411-3607f79bb44c |
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260613024411-3607f79bb44c |
1 more packages
github.com/cloudreve/Cloudreve/v4 Go | All versions | 4.0.0-20260613024411-3607f79bb44c |
How do I fix CVE-2026-55497?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-55497 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55497 exists.
Sources
Also known as GHSA-g9j2-8w95-3vwv, GO-2026-6100.