CVE-2026-33814: Infinite loop in HTTP/2 transport when given bad SETTINGS_MAX_FRAME_SIZE in net/http/internal/http2 in golang.org/x/net

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-07 · updated 2026-10-26
Weakness: CWE-835

Description

When processing HTTP/2 SETTINGS frames, transport will enter an infinite loop of writing CONTINUATION frames if it receives a SETTINGS_MAX_FRAME_SIZE with a value of 0.

Affected products

Go: before 1.25.10; from 1.26.0 before 1.26.3 — fixed in 1.25.10, 1.26.3
Golang Http2: before 0.53.0 — fixed in 0.53.0
Golang.Org/X/Net: before 0.53.0 — fixed in 0.53.0
Go Stdlib: before 1.25.10; from 1.26.0-0 before 1.26.3 — fixed in 1.25.10, 1.26.3

How to fix

Upgrade to a fixed version: Go 1.25.10, 1.26.3; Golang Http2 0.53.0; Golang.Org/X/Net 0.53.0; Go Stdlib 1.25.10, 1.26.3. Check the vendor advisory for mitigations.

References

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