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🛡️ CVE-2026-44981 — crowdsec

⚪ Unknown ✅ No Known Exploit CWE-409 NVD
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: 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

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Attack requirements: Present — the target has to be in a particular state for the attack to work.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-44981 is classified as 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.

Affected software

CVE-2026-44981 is recorded against 2 packages.

  • github.com/crowdsecurity/crowdsec
  • unknown

Timeline and source

Published on 27 May 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Package)
github.com (Web)

Other advisories for this package

github.com/crowdsecurity/crowdsec has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)) in other software:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector 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
CWE CWE-409
Public Exploit ✅ No
Source NVD
Published 2026-05-27
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
github.com/crowdsecurity/crowdsec — —
unknown — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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