Vulnerabilities in pkg:golang/github.com/crowdsecurity/crowdsec

PACKAGE
Advisory Identifier: GHSA-273h-gvwr-c3qj
Advisory Summary

CVE-2026-44981 is a MODERATE denial of service vulnerability (CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)) affecting CrowdSec LAPI libraries in the Go ecosystem. The issue involves denial of service via unbounded gzip decompression. Remediation is available by upgrading affected packages to version 1.7.8.

2 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:golang/github.com/crowdsecurity/crowdsec

2 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:golang/github.com/crowdsecurity/crowdsec. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-273h-gvwr-c3qj CVE-2026-44981 MODERATE CrowdSec LAPI: Denial of Service via Unbounded Gzip Decompression
GHSA-rw47-hm26-6wr7 CVE-2026-44982 HIGH CrowdSec AppSec silently drops request body for chunked / HTTP-2 requests

CVE-2026-44981 at a Glance

CVE Identifier CVE-2026-44981
GHSA Identifier GHSA-273h-gvwr-c3qj
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)
Affected Product CrowdSec LAPI
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-44981

To remediate this vulnerability, upgrade all affected CrowdSec LAPI dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/crowdsecurity/crowdsec fixed: 1.7.8
Upgrade github.com/crowdsecurity/crowdsec to 1.7.8
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

inspect dependencies for github.com/crowdsecurity/crowdsec

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-44981, inspect your project dependencies for CrowdSec LAPI:

inspect dependencies for github.com/crowdsecurity/crowdsec

Analyze the terminal output to locate any version of CrowdSec LAPI in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.7.8), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-409: Improper Handling of Highly Compressed Data (Data Amplification), where the product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output. In CrowdSec LAPI, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-44981 Affected CrowdSec LAPI Versions

1 component(s)
Fixed Versions:
1.7.8
Product / Package Ecosystem Affected Versions Fixed Version
github.com/crowdsecurity/crowdsec
Go
≥ 1.7.0
< 1.7.8
1.7.8

References

Frequently Asked Questions

What is CVE-2026-44981?
CVE-2026-44981 is a security vulnerability in CrowdSec LAPI involving Denial of Service via Unbounded Gzip Decompression under CWE-409: Improper Handling of Highly Compressed Data (Data Amplification).
Which CrowdSec LAPI versions are affected?
Affected versions include releases prior to 1.7.8 across affected packages: github.com/crowdsecurity/crowdsec.
What version fixes CVE-2026-44981?
Upgrading to 1.7.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/crowdsecurity/crowdsec affected?
Yes, github.com/crowdsecurity/crowdsec is affected in releases prior to 1.7.8. Upgrade your dependency to 1.7.8 or later.
What CWE is associated with CVE-2026-44981?
CVE-2026-44981 is classified under CWE-409: Improper Handling of Highly Compressed Data (Data Amplification) (The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.).
How can I check Go dependencies for CVE-2026-44981?
Run the dependency tree command: 'inspect dependencies for github.com/crowdsecurity/crowdsec'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-273h-gvwr-c3qj",
  "modified" : "2026-06-12T20:24:21Z",
  "published" : "2026-05-27T19:57:28Z",
  "aliases" : [ "CVE-2026-44981" ],
  "summary" : "CrowdSec LAPI: Denial of Service via Unbounded Gzip Decompression",
  "details" : "The LAPI router uses `gin-contrib/gzip` with `DefaultDecompressHandle` globally (`pkg/apiserver/controllers/controller.go`).\nThis middleware decompresses incoming request bodies without enforcing a maximum decompressed size. \n\nThe endpoints `/v1/watchers` or `/v1/watchers/login` require no authentication.\nAn attacker can send small gzip-compressed JSON payloads that, when decompressed, result in hundreds of MB of valid JSON occupying server memory.\nSending enough requests concurrently will cause LAPI to allocate excessive heap memory, leading the OS to forcibly terminate the process.\n \nThis vulnerability is not exploitable from the network in default configurations, as LAPI only listens on the loopback interface.\nIf 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.\n \n### Impact\n\nExploiting 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.\n\n### Workarounds\n\nIf 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.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/crowdsecurity/crowdsec"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.7.0"
      }, {
        "fixed" : "1.7.8"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/crowdsecurity/crowdsec/security/advisories/GHSA-273h-gvwr-c3qj"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/crowdsecurity/crowdsec"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/crowdsecurity/crowdsec/releases/tag/v1.7.8"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-409" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-27T19:57:28Z",
    "nvd_published_at" : null
  }
}