CVE-2026-94084
Description
An invalid memory reference vulnerability exists in Suricata's HTTP/2 application-layer engine during multi-buffer management (Http2ThreadMultiBuf). When inspected HTTP/2 response traffic triggers signature rules that evaluate the http.response_header keyword simultaneously with and without sticky buffer transformations, the HTTP/2 state handler improperly reuses allocated memory buffers. An unauthenticated remote attacker can exploit this flaw by transmitting crafted HTTP/2 server response frames across monitored network segments, leading to memory corruption, a daemon crash resulting in Denial of Service (DoS), or potentially arbitrary code execution within the context of the Suricata process. This issue affects Suricata versions prior to 8.0.7.
Statement
A flaw was found in Suricata's HTTP/2 engine (Http2ThreadMultiBuf). When HTTP/2 response traffic is inspected by rules mixing http.response_header with and without transformations, a use-after-free condition occurs. A remote, unauthenticated attacker can exploit this by sending crafted HTTP/2 responses through inspected paths, causing a daemon crash or potentially arbitrary code execution with the privileges of the Suricata process.
Mitigation
Temporarily disable or refactor detection rules that utilize the `http.response_header` keyword with transformations, or disable HTTP/2 protocol parsing by setting `app-layer.protocols.http2.enabled: false` in `/etc/suricata/suricata.yaml` and restart the Suricata service.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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