Improper Handling of Highly Compressed Data (Data Amplification) Affecting authentik-2026.2 package, versions <2026.2.1-r5


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.29% (21st percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-AUTHENTIK20262-16133201
  • published23 Apr 2026
  • disclosed7 Apr 2026

Introduced: 7 Apr 2026

CVE-2026-39373  (opens in a new tab)
CWE-409  (opens in a new tab)

How to fix?

Upgrade Chainguard authentik-2026.2 to version 2026.2.1-r5 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream authentik-2026.2 package and not the authentik-2026.2 package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102 limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7.

CVSS Base Scores

version 3.1