HTTP/2 Rapid reset attack The HTTP/2 protocol allows clients to indicate to the server that a previous stream should be canceled by sending a RSTSTREAM frame. The protocol does not require the client and server to coordinate the cancellation in any way, the client may do it unilaterally. The client may also assume that the cancellation will take effect immediately when the server receives the RSTSTREAM frame, before any other data from that TCP connection is processed.
Abuse of this feature is called a Rapid Reset attack because it relies on the ability for an endpoint to send a RSTSTREAM frame immediately after sending a request frame, which makes the other endpoint start working and then rapidly resets the request. The request is canceled, but leaves the HTTP/2 connection open.
The HTTP/2 Rapid Reset attack built on this capability is simple: The client opens a large number of streams at once as in the standard HTTP/2 attack, but rather than waiting for a response to each request stream from the server or proxy, the client cancels each request immediately.
The ability to reset streams immediately allows each connection to have an indefinite number of requests in flight. By explicitly canceling the requests, the attacker never exceeds the limit on the number of concurrent open streams. The number of in-flight requests is no longer dependent on the round-trip time (RTT), but only on the available network bandwidth.
In a typical HTTP/2 server implementation, the server will still have to do significant amounts of work for canceled requests, such as allocating new stream data structures, parsing the query and doing header decompression, and mapping the URL to a resource. For reverse proxy implementations, the request may be proxied to the backend server before the RSTSTREAM frame is processed. The client on the other hand paid almost no costs for sending the requests. This creates an exploitable cost asymmetry between the server and the client.
Multiple software artifacts implementing HTTP/2 are affected. This advisory was originally ingested from the swift-nio-http2 repo advisory and their original conent follows.
swift-nio-http2 specific advisory swift-nio-http2 is vulnerable to a denial-of-service vulnerability in which a malicious client can create and then reset a large number of HTTP/2 streams in a short period of time. This causes swift-nio-http2 to commit to a large amount of expensive work which it then throws away, including creating entirely new Channels to serve the traffic. This can easily overwhelm an EventLoop and prevent it from making forward progress.
swift-nio-http2 1.28 contains a remediation for this issue that applies reset counter using a sliding window. This constrains the number of stream resets that may occur in a given window of time. Clients violating this limit will have their connections torn down. This allows clients to continue to cancel streams for legitimate reasons, while constraining malicious actors.
An Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability [CWE-79] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.6, FortiOS 7.4 all versions, FortiOS 7.2 all versions, FortiPAM 1.8.0, FortiPAM 1.7 all versions, FortiPAM 1.6 all versions, FortiPAM 1.5 all versions, FortiPAM 1.4 all versions, FortiPAM 1.3 all versions, FortiPAM 1.2 all versions, FortiPAM 1.1 all versions, FortiPAM 1.0 all versions, FortiProxy 7.4.0 through 7.4.3, FortiProxy 7.2.0 through 7.2.9 may allow an authenticated remote user to execute code or commands via crafted requests.
A buffer over-read vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions may allow an authenticated remote attacker to return a portion of device memory in the redirect response via submitting a specially crafted request.
An Internal Asset Exposed to Unsafe Debug Access Level or State vulnerability [CWE-1244] vulnerability in Fortinet FortiOS 7.6.0 through 7.6.2, FortiOS 7.4.0 through 7.4.7, FortiOS 7.2.0 through 7.2.10, FortiOS 7.0.0 through 7.0.16, FortiOS 6.4 all versions, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.10, FortiProxy 7.2.0 through 7.2.14, FortiProxy 7.0 all versions may allow an authenticated admin to execute lua scripts via crafted CLI commands.
An improper verification of cryptographic signature vulnerability in Fortinet FortiWeb 8.0.0, FortiWeb 7.6.0 through 7.6.4, FortiWeb 7.4.0 through 7.4.9 may allow an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.
A improper verification of cryptographic signature vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4.0 through 7.4.8, FortiOS 7.2.0 through 7.2.11, FortiOS 7.0.0 through 7.0.17, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.10, FortiProxy 7.2.0 through 7.2.14, FortiProxy 7.0.0 through 7.0.21, FortiSwitchManager 7.2.0 through 7.2.6, FortiSwitchManager 7.0.0 through 7.0.5 allows an unauthenticated attacker to bypass the FortiCloud SSO login authentication via a crafted SAML response message.
An Heap-based Buffer Overflow vulnerability [CWE-122] in FortiOS version 7.6.2 and below, version 7.4.7 and below, version 7.2.10 and below, 7.0 all versions, 6.4 all versions; FortiPAM version 1.5.0, version 1.4.2 and below, 1.3 all versions, 1.2 all versions, 1.1 all versions, 1.0 all versions and FortiProxy version 7.6.2 and below, version 7.4.3 and below, 7.2 all versions, 7.0 all versions RDP bookmark connection may allow an authenticated user to execute unauthorized code via crafted requests.
A insertion of sensitive information into log file vulnerability in Fortinet FortiOS 7.6.0 through 7.6.3, FortiOS 7.4 all versions, FortiOS 7.2 all versions, FortiOS 7.0 all versions, FortiOS 6.4 all versions, FortiProxy 7.6.0 through 7.6.3, FortiProxy 7.4.0 through 7.4.13, FortiProxy 7.2 all versions, FortiProxy 7.0 all versions may allow attacker to information disclosure via <insert attack vector here>
An Integer Overflow or Wraparound vulnerability [CWE-190] in FortiOS version 7.6.2 and below, version 7.4.7 and below, version 7.2.10 and below, 7.2 all versions, 6.4 all versions, FortiProxy version 7.6.2 and below, version 7.4.3 and below, 7.2 all versions, 7.0 all versions, 2.0 all versions and FortiPAM version 1.5.0, version 1.4.2 and below, 1.3 all versions, 1.2 all versions, 1.1 all versions, 1.0 all versions SSL-VPN RDP and VNC bookmarks may allow an authenticated user to affect the device SSL-VPN availability via crafted requests.
An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] in FortiOS 7.4.0 through 7.4.7, 7.2.0 through 7.2.11, 7.0.6 and above; and FortiProxy 7.6.0 through 7.6.2, 7.4.0 through 7.4.8, 7.2 all versions, 7.0.5 and above may allow an authenticated attacker to elevate their privileges via triggering a malicious Webhook action in the Automation Stitch component.
An Improperly Implemented Security Check for Standard vulnerability [CWE-358] in FortiOS and FortiProxy may allow a remote unauthenticated user to bypass the DNS filter via Apple devices.
A out-of-bounds write in Fortinet FortiOS versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.6, 7.0.0 through 7.0.13, 6.4.0 through 6.4.14, 6.2.0 through 6.2.15, 6.0.0 through 6.0.17, FortiProxy versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.8, 7.0.0 through 7.0.14, 2.0.0 through 2.0.13, 1.2.0 through 1.2.13, 1.1.0 through 1.1.6, 1.0.0 through 1.0.7 allows attacker to execute unauthorized code or commands via specifically crafted requests
A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiManager 7.6.0 through 7.6.1, FortiManager 7.4.1 through 7.4.3, FortiManager Cloud 7.4.1 through 7.4.3, FortiOS 7.6.0, FortiOS 7.4.0 through 7.4.4, FortiOS 7.2.0 through 7.2.9, FortiOS 7.0.0 through 7.0.15, FortiOS 6.4.0 through 6.4.15, FortiProxy 7.4.0 through 7.4.5, FortiProxy 7.2.0 through 7.2.11, FortiProxy 7.0.0 through 7.0.18, FortiProxy 2.0 all versions, FortiProxy 1.2 all versions, FortiProxy 1.1 all versions, FortiProxy 1.0 all versions may allow a remote authenticated attacker with access to the security fabric interface and port to write arbitrary files or a remote unauthenticated attacker to delete an arbitrary folder
A improper limitation of a pathname to a restricted directory ('path traversal') vulnerability in Fortinet FortiRecorder 7.2.0 through 7.2.1, FortiRecorder 7.0.0 through 7.0.4, FortiVoice 7.0.0 through 7.0.4, FortiVoice 6.4.0 through 6.4.9, FortiVoice 6.0 all versions, FortiWeb 7.6.0, FortiWeb 7.4.0 through 7.4.4, FortiWeb 7.2 all versions, FortiWeb 7.0 all versions, FortiWeb 6.4 all versions allows attacker to escalate privilege via specially crafted packets.
A stack-based buffer overflow vulnerability in Fortinet FortiOS 7.4.0 through 7.4.1, FortiOS 7.2.0 through 7.2.5, FortiOS 7.0.0 through 7.0.12, FortiOS 6.4.0 through 6.4.14, FortiOS 6.2.0 through 6.2.15, FortiProxy 7.4.0, FortiProxy 7.2.0 through 7.2.6, FortiProxy 7.0.0 through 7.0.12, FortiProxy 2.0.0 through 2.0.13, FortiSASE 23.2.b allows attacker to execute unauthorized code or commands via specially crafted HTTP requests.
A out-of-bounds write vulnerability in Fortinet FortiOS 7.4.0 through 7.4.1, FortiOS 7.2.0 through 7.2.5, FortiOS 7.0.0 through 7.0.12, FortiOS 6.4.0 through 6.4.14, FortiOS 6.2.0 through 6.2.15, FortiProxy 7.4.0, FortiProxy 7.2.0 through 7.2.6, FortiProxy 7.0.0 through 7.0.12, FortiProxy 2.0.0 through 2.0.13, FortiSASE 23.2.b allows attacker to execute unauthorized code or commands via specially crafted HTTP requests.
An Authentication Bypass Using an Alternate Path or Channel vulnerability [CWE-288] in FortiOS, FortiManager, FortiAnalyzer, FortiProxy, FortiSwitchManager, FortiWeb may allow an attacker with a FortiCloud account and a registered device to log into other devices registered to other accounts, if FortiCloud SSO authentication is enabled on those devices.Please note that the FortiCloud SSO login feature is not enabled in default factory settings. However, when an administrator registers the device to FortiCare from the device's GUI, unless the administrator disables the toggle switch "Allow administrative login using FortiCloud SSO" in the registration page, FortiCloud SSO login is enabled upon registration. This vulnerability was found being exploited in the wild by two malicious FortiCloud accounts, which were locked out on 2026-01-22. In order to protect its customers from further exploit, Fortinet disabled FortiCloud SSO on FortiCloud side on 2026-01-26. It was re-enabled on 2026-01-27 and no longer supports login from devices running vulnerable versions. Consequently, customers must upgrade to the latest versions listed below for the FortiCloud SSO authentication to function.FortiManager Cloud, FortiAnalyzer Cloud, FortiGate Cloud are NOT impacted.Setups with Custom IdP for SSO instead of FortiCloud are not impacted (including setups using FortiAuthenticator as the Custom IdP)
A use of externally-controlled format string in Fortinet FortiOS versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.6, 7.0.0 through 7.0.13, FortiProxy versions 7.4.0 through 7.4.2, 7.2.0 through 7.2.8, 7.0.0 through 7.0.14, FortiPAM versions 1.2.0, 1.1.0 through 1.1.2, 1.0.0 through 1.0.3, FortiSwitchManager versions 7.2.0 through 7.2.3, 7.0.0 through 7.0.3 allows attacker to execute unauthorized code or commands via specially crafted packets.
A fundamental design flaw within the RADIUS protocol has been proven to be exploitable, compromising the integrity in the RADIUS Access-Request process. The attack allows a malicious user to modify packets in a way that would be indistinguishable to a RADIUS client or server. To be successful, the attacker must have the ability to inject themselves between the client and server.
An Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') [CWE-22] in the command line interpreter of FortiOS, FortiPAM, FortiProxy and FortiSwitchManager may allow a privileged attacker to achieve arbitrary write or delete files via specifically crafted arguments to existing commands.
An authentication bypass using an alternate path or channel [CWE-288] vulnerability in Fortinet FortiOS 6.4.0 through 6.4.15, FortiOS 6.2.0 through 6.2.16, FortiOS 6.0 all versions, FortiPAM 1.2.0, FortiPAM 1.1.0 through 1.1.2, FortiPAM 1.0.0 through 1.0.3, FortiProxy 7.4.0 through 7.4.2, FortiProxy 7.2.0 through 7.2.8, FortiProxy 7.0.0 through 7.0.15, FortiSwitchManager 7.2.0 through 7.2.3, FortiSwitchManager 7.0.0 through 7.0.3 allows an unauthenticated attacker to seize control of a managed device via crafted FGFM requests, if the device is managed by a FortiManager, and if the attacker knows that FortiManager's serial number.
An Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') [CWE-22] in the command line interpreter of FortiOS, FortiPAM, FortiProxy and FortiSwitchManager may allow a privileged attacker to achieve arbitrary write or delete files via specifically crafted arguments to existing commands.
A use of externally-controlled format string vulnerability [CWE-134] in FortiOS version 7.4.0 through 7.4.4, version 7.2.0 through 7.2.9, version 7.0.0 through 7.0.15 and before 6.4.15, FortiProxy version 7.4.0 through 7.4.6, version 7.2.0 through 7.2.12 and before 7.0.19, FortiPAM version 1.4.0 through 1.4.2 and before 1.3.1, FortiSRA version 1.4.0 through 1.4.2 and before 1.3.1 and FortiWeb version 7.4.0 through 7.4.5, version 7.2.0 through 7.2.10 and before 7.0.10 allows a privileged attacker to execute unauthorized code or commands via specially crafted HTTP or HTTPS commands.
An improper neutralization of input during web page Generation vulnerability [CWE-79] in FortiOS and FortiProxy's web SSL VPN UI may allow a remote unauthenticated attacker to perform a Cross-Site Scripting attack via social engineering the targeted user into bookmarking a malicious samba server, then opening the bookmark.
A improper restriction of communication channel to intended endpoints vulnerability [CWE-923] in Fortinet FortiOS version 7.4.0 through 7.4.4, 7.2.0 through 7.2.8, 7.0.0 through 7.0.15, 6.4.0 through 6.4.15 and before 6.2.16, Fortinet FortiProxy version 7.4.0 through 7.4.2, 7.2.0 through 7.2.9 and before 7.0.15, Fortinet FortiManager version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and before 6.2.13, Fortinet FortiAnalyzer version 7.4.0 through 7.4.2, 7.2.0 through 7.2.4, 7.0.0 through 7.0.11, 6.4.0 through 6.4.14 and before 6.2.13, Fortinet FortiVoice version 7.0.0 through 7.0.2 before 6.4.8 and Fortinet FortiWeb before 7.4.2 may allow an unauthenticated attacker in a man-in-the-middle position to impersonate the management device (FortiCloud server or/and in certain conditions, FortiManager), via intercepting the FGFM authentication request between the management device and the managed device
An Improper Privilege Management vulnerability [CWE-269] affecting FortiOS, FortiProxy & FortiWeb may allow an authenticated attacker with at least read-only admin permissions to gain super-admin privileges via crafted requests to Node.js websocket module.
A double free vulnerability [CWE-415] in FortiOS, FortiProxy & FortiPAM administrative interfaces may allow a privileged attacker to execute code or commands via crafted HTTP or HTTPs requests.
A heap-based buffer overflow in Fortinet FortiSRA 1.5.0, 1.4.0 through 1.4.2, FortiPAM 1.5.0, 1.4.0 through 1.4.2, 1.3.0 through 1.3.1, 1.2.0, 1.1.0 through 1.1.2, 1.0.0 through 1.0.3, FortiProxy 7.6.0 through 7.6.1, 7.4.0 through 7.4.7, FortiOS 7.6.0 through 7.6.2, 7.4.0 through 7.4.6, 7.2.0 through 7.2.10, 7.0.2 through 7.0.16, FortiSwitchManager 7.2.1 through 7.2.5 allows attackers to escalate their privilege via specially crafted http requests.
A heap-based buffer overflow vulnerability [CWE-122] in FortiOS, FortiManager, FortiAnalyzer, FortiManager Cloud, FortiAnalyzer Cloud, FortiProxy fgfmd daemon may allow an authenticated attacker to execute arbitrary code or commands via specifically crafted requests.
A stack-based buffer overflow in Fortinet FortiOS version 7.4.0 through 7.4.1 and 7.2.0 through 7.2.7 and 7.0.0 through 7.0.12 and 6.4.6 through 6.4.15 and 6.2.9 through 6.2.16 and 6.0.13 through 6.0.18 allows attacker to execute unauthorized code or commands via specially crafted CLI commands.