CVE-2025-53538: Suricata's mishandling of data on HTTP2 stream 0 can lead to resource starvation

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-22 · updated 2026-06-17
Weakness: CWE-400

Description

Suricata is a network IDS, IPS and NSM engine developed by the OISF (Open Information Security Foundation) and the Suricata community. In versions 7.0.10 and below and 8.0.0-beta1 through 8.0.0-rc1, mishandling of data on HTTP2 stream 0 can lead to uncontrolled memory usage, leading to loss of visibility. Workarounds include disabling the HTTP/2 parser, and using a signature like drop http2 any any -> any any (frame:http2.hdr; byte_test:1,=,0,3; byte_test:4,=,0,5; sid: 1;) where the first byte test tests the HTTP2 frame type DATA and the second tests the stream id 0. This is fixed in versions 7.0.11 and 8.0.0.

Affected products

OISF suricata: before 7.0.11; 8.0.0-beta1, 8.0.0-rc1 — fixed in 7.0.11

How to fix

Upgrade to a fixed version: OISF suricata 7.0.11. Check the vendor advisory for mitigations.

References

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