CrowdSec LAPI: Denial of Service via Unbounded Gzip Decompression

The LAPI router uses `gin-contrib/gzip` with `DefaultDecompressHandle` globally (`pkg/apiserver/controllers/controller.go`). This middleware decompresses incoming request bodies without enforcing a maximum decompressed size. The endpoints `/v1/watchers` or `/v1/watchers/login` require no authentication. An attacker can send small gzip-compressed JSON payloads that, when decompressed, result in hundreds of MB of valid JSON occupying server memory. Sending enough requests concurrently will cause LAPI to allocate excessive heap memory, leading the OS to forcibly terminate the process. This vulnerability is not exploitable from the network in default configurations, as LAPI only listens on the loopback interface. If developers' applications are using a multi-server setup, LAPI will be exposed in the network, in which case they are at risk if untrusted IPs can access it. ### Impact Exploiting this vulnerability will make LAPI unreachable, meaning that bouncers will not be able to fetch new decisions (but existing decisions will still be enforced) and log processors will not be able to send alerts, effectively denying the creation of new decisions. ### Workarounds If the LAPI is exposed on the network (either directly or through a reverse proxy), for example in the case of a multi-server deployment, restrict access to trusted IP addresses.

Source published

27 May 2026 19:57:28 UTC

Source modified

17 Jun 2026 00:26:11 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

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