CVE-2026-62160: Daptin: ParseAcceptLanguage `_` separator bypass enables >250x CPU amplification via Accept-Language header in LanguageMiddleware

Severity: high (CVSS 8.7 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-30 · updated 2026-10-30
Weakness: CWE-400

Description

Daptin is a GraphQL/JSON-API headless CMS. Prior to 0.12.26, the global `LanguageMiddleware` in `server/language.go` passes the raw `Accept-Language` header from `LanguageMiddlewareFunc` through `GetLanguagePreference` to `golang.org/x/text/language.ParseAcceptLanguage` without a size or shape filter. The guard for CVE-2022-32149 counts hyphens but not underscores, even though the internal parser normalizes underscores to hyphens. Long lists of underscore-separated language subtags longer than eight characters bypass the guard. These subtags fail the `len <= 8` length check in `golang.org/x/text/internal/language/parse.go`, causing repeated `gobble` operations to move the entire remaining buffer through `runtime.memmove`. With many invalid subtags, this repeated buffer movement takes quadratic work. Unauthenticated requests to the public landing page or `/api` can consume disproportionate CPU, with a 256 KiB header already causing seconds of processing and larger input permitted by the default 1 MiB header ceiling. `resource.CheckErr` also logs the entire invalid header, amplifying cost, while normal successful HTTP responses can conceal the denial-of-service traffic. Repeated requests can saturate server CPU. This issue is fixed in version 0.12.26.

Affected products

Go Github.Com/Daptin/Daptin: through 0.12.15
daptin: before 0.12.26

References

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