🐛 fix appsec bypass with invalid content-length#321
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mathieuHa
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This looks good to me
HTTP/1.1 allows chunked transfer encoding, where Content-Length is absent or misleading. An attacker can craft a request with a body but no valid Content-Length, and the code before would skip AppSec analysis completely on that body. This could be an AppSec bypass vector.
A bit of context for users:
An attacker could bypass AppSec inspection entirely by sending a request with a body but setting Content-Length: 0 (or omitting the header entirely, which defaults to -1 in Go's http.Request). Since ContentLength <= 0 was falsy in the condition, the body would never be forwarded to AppSec for analysis, even though it contained potentially malicious payload.
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…plugin to v1.6.0 ##### [\`v1.6.0\`](https://github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/releases/tag/v1.6.0) #### What's Changed - 📝 Update README.md to show simplified dynamic configuration by [@cliffjao](https://github.com/cliffjao) in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) - 🔊 Improve Logging: move to slog and add trace level by [@david-garcia-garcia](https://github.com/david-garcia-garcia) in [#276](maxlerebourg/crowdsec-bouncer-traefik-plugin#276) - 🐛 fix appsec bypass with invalid content-length by [@maxlerebourg](https://github.com/maxlerebourg) in [#321](maxlerebourg/crowdsec-bouncer-traefik-plugin#321) #### New Contributors - [@cliffjao](https://github.com/cliffjao) made their first contribution in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) **Full Changelog**: <maxlerebourg/crowdsec-bouncer-traefik-plugin@v1.5.1...v1.6.0>
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…plugin to v1.6.0 ##### [\`v1.6.0\`](https://github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/releases/tag/v1.6.0) #### What's Changed - 📝 Update README.md to show simplified dynamic configuration by [@cliffjao](https://github.com/cliffjao) in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) - 🔊 Improve Logging: move to slog and add trace level by [@david-garcia-garcia](https://github.com/david-garcia-garcia) in [#276](maxlerebourg/crowdsec-bouncer-traefik-plugin#276) - 🐛 fix appsec bypass with invalid content-length by [@maxlerebourg](https://github.com/maxlerebourg) in [#321](maxlerebourg/crowdsec-bouncer-traefik-plugin#321) #### New Contributors - [@cliffjao](https://github.com/cliffjao) made their first contribution in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) **Full Changelog**: <maxlerebourg/crowdsec-bouncer-traefik-plugin@v1.5.1...v1.6.0>
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…plugin to v1.6.0 ##### [\`v1.6.0\`](https://github.com/maxlerebourg/crowdsec-bouncer-traefik-plugin/releases/tag/v1.6.0) #### What's Changed - 📝 Update README.md to show simplified dynamic configuration by [@cliffjao](https://github.com/cliffjao) in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) - 🔊 Improve Logging: move to slog and add trace level by [@david-garcia-garcia](https://github.com/david-garcia-garcia) in [#276](maxlerebourg/crowdsec-bouncer-traefik-plugin#276) - 🐛 fix appsec bypass with invalid content-length by [@maxlerebourg](https://github.com/maxlerebourg) in [#321](maxlerebourg/crowdsec-bouncer-traefik-plugin#321) #### New Contributors - [@cliffjao](https://github.com/cliffjao) made their first contribution in [#313](maxlerebourg/crowdsec-bouncer-traefik-plugin#313) **Full Changelog**: <maxlerebourg/crowdsec-bouncer-traefik-plugin@v1.5.1...v1.6.0>
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A bidirectional gRPC stream is an HTTP/2 request with no Content-Length whose body never reaches EOF. Since #321 removed the ContentLength guard, appsecQuery buffered it with io.ReadAll, which blocked until the request timed out and was turned into a 403 (issue #323). The backend was never reached (OriginStatus:0). Mirror the reference lua-cs-bouncer behaviour: detect an unreadable body (ProtoMajor >= 2 && ContentLength < 0) and, instead of buffering it, forward the request to Appsec with headers only. Add a new CrowdsecAppsecDropUnreadableBody option (default false) that mirrors the reference APPSEC_DROP_UNREADABLE_BODY: when true, such requests are blocked outright instead of forwarded without their body. Readable HTTP/1.1 bodies are still buffered and inspected, so the bypass closed by #321 stays closed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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