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.

An improper check or handling of exceptional conditions vulnerability [CWE-703] in FortiOS version 7.4.0 through 7.4.3 and before 7.2.7, FortiProxy version 7.4.0 through 7.4.3 and before 7.2.9, FortiPAM before 1.2.0 and FortiSwitchManager version 7.2.0 through 7.2.3 and version 7.0.0 through 7.0.3 fgfm daemon may allow an unauthenticated attacker to repeatedly reset the fgfm connection via crafted SSL encrypted TCP requests.

Apache HTTP Server: modhttp2 denial of service

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 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.

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.

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 insertion of sensitive information into sent data vulnerability in Fortinet FortiMail 7.4.0 through 7.4.2, FortiMail 7.2.0 through 7.2.6, FortiMail 7.0 all versions, 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, FortiNDR 7.6.0 through 7.6.1, FortiNDR 7.4.0 through 7.4.8, FortiNDR 7.2 all versions, FortiNDR 7.1 all versions, FortiNDR 7.0 all versions, FortiNDR 1.5 all versions, FortiOS 7.6.0, FortiOS 7.4.0 through 7.4.4, FortiOS 7.2.0 through 7.2.8, FortiOS 7.0.0 through 7.0.15, FortiOS 6.4.0 through 6.4.15, FortiOS 6.2 all versions, FortiOS 6.0 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 7.4.4, FortiProxy 7.2.0 through 7.2.10, FortiProxy 7.0 all versions, FortiProxy 2.0 all versions, FortiProxy 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 all versions, FortiRecorder 7.2.0 through 7.2.1, FortiRecorder 7.0.0 through 7.0.4, FortiTester 7.4.0 through 7.4.2, FortiTester 7.3 all versions, FortiTester 7.2 all versions, FortiTester 7.1 all versions, FortiTester 7.0 all versions, FortiTester 4.2 all versions, FortiVoice 7.0.0 through 7.0.4, FortiVoice 6.4.0 through 6.4.9, FortiVoice 6.0.7 through 6.0.12, 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 disclose sensitive information via specially crafted packets.

A out-of-bounds write vulnerability [CWE-787] in FortiOS and FortiProxy may allow a remote unauthenticated attacker to execute arbitrary code or command via specially crafted HTTP requests.

Workaround : disable SSL VPN (disable webmode is NOT a valid workaround)

Note: This is potentially being exploited in the wild.

A missing authentication for critical function vulnerability in Fortinet FortiManager 7.4.0 through 7.4.2, FortiManager 7.2.0 through 7.2.4, FortiManager 7.0.0 through 7.0.11, FortiManager 6.4.0 through 6.4.14, FortiOS 7.4.0 through 7.4.3, FortiOS 7.2.0 through 7.2.7, FortiOS 7.0.0 through 7.0.14, FortiOS 6.4 all versions, FortiOS 6.2 all versions, FortiOS 6.0 all versions, FortiPAM 1.2 all versions, FortiPAM 1.1 all versions, FortiPAM 1.0 all versions, FortiPortal 6.0.0 through 6.0.14, FortiPortal 5.3 all versions, FortiProxy 7.4.0 through 7.4.3, FortiProxy 7.2.0 through 7.2.9, FortiProxy 7.0.0 through 7.0.16, FortiProxy 2.0 all versions, FortiProxy 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 all versions, FortiSwitchManager 7.2.0 through 7.2.3, FortiSwitchManager 7.0.0 through 7.0.3 allows attacker to execute unauthorized code or commands via specially crafted packets.

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 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 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 stack-based buffer overflow vulnerability in Fortinet FortiOS 7.4.0 through 7.4.3, FortiOS 7.2.0 through 7.2.7, FortiOS 7.0.0 through 7.0.14, FortiOS 6.4 all versions, FortiOS 6.2 all versions, FortiOS 6.0 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, FortiProxy 7.0.0 through 7.0.16, FortiProxy 2.0 all versions, FortiProxy 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 all versions, FortiSwitchManager 7.2.0 through 7.2.3, FortiSwitchManager 7.0.1 through 7.0.3 allows attacker to execute unauthorized code or commands via specially crafted packets.

A insufficiently protected credentials vulnerability in Fortinet FortiOS 7.4.0 through 7.4.1, FortiOS 7.2.0 through 7.2.6, FortiOS 7.0.0 through 7.0.12, FortiOS 6.4.0 through 6.4.14, FortiOS 6.2.0 through 6.2.15, FortiOS 6.0 all versions, FortiProxy 7.4.0 through 7.4.1, FortiProxy 7.2.0 through 7.2.7, FortiProxy 7.0.0 through 7.0.13, FortiProxy 2.0 all versions, FortiProxy 01.02 all versions, FortiProxy 1.2 all versions, FortiProxy 01.01 all versions, FortiProxy 1.1 all versions, FortiProxy 01.00 all versions allows attacker to execute unauthorized code or commands via targeted social engineering attack

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 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 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.

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.

An insertion of sensitive information into log file vulnerability [CWE-532] in FortiOS 7.4.0 through 7.4.3, 7.2.0 through 7.2.7, 7.0 all versions; FortiProxy 7.4.0 through 7.4.3, 7.2.0 through 7.2.11; FortiPAM 1.4 all versions, 1.3 all versions, 1.2 all versions, 1.1 all versions, 1.0 all versions and FortiSRA 1.4 all versions may allow a read-only administrator to retrieve API tokens of other administrators via observing REST API logs, if REST API logging is enabled (non-default configuration).

CVE-2026-49975Memory Allocation with Excessive Size Value vulnerability in Apache HTTP Server's modhttp leads to denial of service via malicious HTTP requests. This issue affects Apache HTTP Server: from 2.4.17 through 2.4.67.

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)