Cesanta Mongoose

Mongoose Web Server 6.9 DoS via Multiple Socket Connections
CVE-2018-25193 7.5 - High - March 06, 2026

Mongoose Web Server 6.9 contains a denial of service vulnerability that allows remote attackers to crash the service by establishing multiple socket connections. Attackers can repeatedly create connections to the default port and send malformed data to exhaust server resources and cause service unavailability.

Insecure Default Initialization of Resource

Cesanta Mongoose <=7.20 Poly1305 Tag Handler Signature Verification Bypass
CVE-2026-2968 3.7 - Low - February 23, 2026

A vulnerability was detected in Cesanta Mongoose up to 7.20. This impacts the function mg_chacha20_poly1305_decrypt of the file /src/tls_chacha20.c of the component Poly1305 Authentication Tag Handler. The manipulation results in improper verification of cryptographic signature. The attack may be launched remotely. This attack is characterized by high complexity. The exploitability is said to be difficult. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Improper Verification of Cryptographic Signature

Cesanta Mongoose <=7.20 TCPSN Handler Getpeer Remote Sequence Num Bypass
CVE-2026-2967 3.7 - Low - February 23, 2026

A security vulnerability has been detected in Cesanta Mongoose up to 7.20. This affects the function getpeer of the file /src/net_builtin.c of the component TCP Sequence Number Handler. The manipulation leads to improper verification of source of a communication channel. The attack may be initiated remotely. The attack's complexity is rated as high. The exploitability is reported as difficult. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Improper Verification of Source of a Communication Channel

Cesanta Mongoose7.20 DNS Txn ID Handler Randomness Weakness
CVE-2026-2966 3.7 - Low - February 23, 2026

A weakness has been identified in Cesanta Mongoose up to 7.20. The impacted element is the function mg_sendnsreq of the file /src/dns.c of the component DNS Transaction ID Handler. Executing a manipulation of the argument random can lead to insufficiently random values. The attack can be launched remotely. The attack requires a high level of complexity. The exploitability is regarded as difficult. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.

Use of Insufficiently Random Values

Cesanta Mongoose <7.2 NOPTRD in add_ca_certs() TLS DoS
CVE-2025-65502 4.3 - Medium - November 24, 2025

Null pointer dereference in add_ca_certs() in Cesanta Mongoose before 7.2 allows remote attackers to cause a denial of service via TLS initialization where SSL_CTX_get_cert_store() returns NULL.

NULL Pointer Dereference

Cesanta Mongoose Web Server: Use of Out-of-range Pointer Offset Vulnerability
CVE-2024-42387 5.3 - Medium - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and force the application to read unintended heap memory space.

Untrusted pointer offset

Cesanta Mongoose Web Server: Out-of-range Pointer Offset Vulnerability in TLS Handling
CVE-2024-42388 5.3 - Medium - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and force the application to read unintended heap memory space.

Untrusted pointer offset

Cesanta Mongoose Web Server: Use of Out-of-range Pointer Offset Vulnerability
CVE-2024-42389 5.3 - Medium - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and force the application to read unintended heap memory space.

Untrusted pointer offset

Cesanta Mongoose Web Server: Out-of-range Pointer Offset Vulnerability in TLS Handling
CVE-2024-42390 5.3 - Medium - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and force the application to read unintended heap memory space.

Untrusted pointer offset

Cesanta Mongoose Web Server: Out-of-range Pointer Offset Vulnerability in TLS Handling
CVE-2024-42391 5.3 - Medium - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and force the application to read unintended heap memory space.

Untrusted pointer offset

Cesanta Mongoose Web Server: Improper Neutralization of Delimiters Leading to Infinite Loop
CVE-2024-42392 7.5 - High - November 18, 2024

Improper Neutralization of Delimiters vulnerability in Cesanta Mongoose Web Server v7.14 allows to trigger an infinite loop bug if the input string contains unexpected characters.

Improper Neutralization of Delimiters

Cesanta Mongoose Web Server: Use of Out-of-range Pointer Offset in TLS Handling
CVE-2024-42386 7.5 - High - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and produce a segmentation fault on the application.

Untrusted pointer offset

Cesanta Mongoose Web Server: Improper Neutralization of Delimiters Leading to Out-of-Bounds Memory W
CVE-2024-42385 7 - High - November 18, 2024

Improper Neutralization of Delimiters vulnerability in Cesanta Mongoose Web Server v7.14 allows to trigger an out-of-bound memory write if the PEM certificate contains unexpected characters.

Improper Neutralization of Delimiters

Cesanta Mongoose Web Server v7.14 TLS Packet Handling Integer Overflow Vulnerability
CVE-2024-42384 7.5 - High - November 18, 2024

Integer Overflow or Wraparound vulnerability in Cesanta Mongoose Web Server v7.14 allows an attacker to send an unexpected TLS packet and produce a segmentation fault on the application.

Integer Overflow or Wraparound

Cesanta Mongoose Web Server: Out-of-range Pointer Offset Vulnerability
CVE-2024-42383 9.8 - Critical - November 18, 2024

Use of Out-of-range Pointer Offset vulnerability in Cesanta Mongoose Web Server v7.14 allows to write a NULL byte value beyond the memory space dedicated for the hostname field.

Untrusted pointer offset

Cesanta Mongoose MQTT Null Pointer Deref in scpy (DoS)
CVE-2024-35492 - May 29, 2024

Cesanta Mongoose commit b316989 was discovered to contain a NULL pointer dereference via the scpy function at src/fmt.c. This vulnerability allows attackers to cause a Denial of Service (DoS) via a crafted MQTT packet.

BUFOVF in Mongoose 6.18 mg_resolve_from_hosts_file
CVE-2020-25887 8.8 - High - August 22, 2023

Buffer overflow in mg_resolve_from_hosts_file in Mongoose 6.18, when reading from a crafted hosts file.

Classic Buffer Overflow

Cesanta Mongoose 7.10 Heap Overflow via MQTT Publish Header
CVE-2023-2905 8.8 - High - August 09, 2023

Due to a failure in validating the length of a provided MQTT_CMD_PUBLISH parsed message with a variable length header, Cesanta Mongoose, an embeddable web server, version 7.10 is susceptible to a heap-based buffer overflow vulnerability in the default configuration. Version 7.9 and prior does not appear to be vulnerable. This issue is resolved in version 7.11.

Memory Corruption

Mongoose <7.10 HTTP Server Nega Content-Length Infinite Loop DDoS
CVE-2023-34188 7.5 - High - June 23, 2023

The HTTP server in Mongoose before 7.10 accepts requests containing negative Content-Length headers. By sending a single attack payload over TCP, an attacker can cause an infinite loop in which the server continuously reparses that payload, and does not respond to any other requests.

This affects the package cesanta/mongoose before 7.6
CVE-2022-25299 7.5 - High - February 18, 2022

This affects the package cesanta/mongoose before 7.6. The unsafe handling of file names during upload using mg_http_upload() method may enable attackers to write files to arbitrary locations outside the designated target folder.

Files or Directories Accessible to External Parties

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 (compiled with OpenSSL support) is vulnerable to remote OOB write attack
CVE-2021-26530 9.1 - Critical - February 08, 2021

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 (compiled with OpenSSL support) is vulnerable to remote OOB write attack via connection request after exhausting memory pool.

Memory Corruption

The mg_http_serve_file function in Cesanta Mongoose HTTP server 7.0 is vulnerable to remote OOB write attack
CVE-2021-26528 9.1 - Critical - February 08, 2021

The mg_http_serve_file function in Cesanta Mongoose HTTP server 7.0 is vulnerable to remote OOB write attack via connection request after exhausting memory pool.

Memory Corruption

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 and 6.7-6.18 (compiled with mbedTLS support) is vulnerable to remote OOB write attack
CVE-2021-26529 9.1 - Critical - February 08, 2021

The mg_tls_init function in Cesanta Mongoose HTTPS server 7.0 and 6.7-6.18 (compiled with mbedTLS support) is vulnerable to remote OOB write attack via connection request after exhausting memory pool.

Memory Corruption

A buffer overflow vulnerability exists in the mg_get_http_header function in Cesanta Mongoose 6.18 due to a lack of bounds checking
CVE-2020-25756 9.8 - Critical - September 18, 2020

A buffer overflow vulnerability exists in the mg_get_http_header function in Cesanta Mongoose 6.18 due to a lack of bounds checking. A crafted HTTP header can exploit this bug. NOTE: a committer has stated "this will not happen in practice.

Classic Buffer Overflow

An integer overflow in parse_mqtt in mongoose.c in Cesanta Mongoose 6.16
CVE-2019-19307 - November 26, 2019

An integer overflow in parse_mqtt in mongoose.c in Cesanta Mongoose 6.16 allows an attacker to achieve remote DoS (infinite loop), or possibly cause an out-of-bounds write, by sending a crafted MQTT protocol packet.

mq_parse_http in mongoose.c in Mongoose 6.15 has a heap-based buffer over-read.
CVE-2019-13503 - July 11, 2019

mq_parse_http in mongoose.c in Mongoose 6.15 has a heap-based buffer over-read.

An issue was discovered in Mongoose before 6.15
CVE-2019-12951 - June 24, 2019

An issue was discovered in Mongoose before 6.15. The parse_mqtt() function in mg_mqtt.c has a critical heap-based buffer overflow.

An invalid read of 8 bytes due to a use-after-free vulnerability during a "return" in the mg_http_get_proto_data function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier
CVE-2018-20354 - June 10, 2019

An invalid read of 8 bytes due to a use-after-free vulnerability during a "return" in the mg_http_get_proto_data function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.

An invalid write of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi function call in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier
CVE-2018-20355 - June 10, 2019

An invalid write of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi function call in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.

An invalid read of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi function call in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier
CVE-2018-20356 - June 10, 2019

An invalid read of 8 bytes due to a use-after-free vulnerability in the mg_http_free_proto_data_cgi function call in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.

An invalid read of 8 bytes due to a use-after-free vulnerability during a "NULL test" in the mg_http_get_proto_data function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier
CVE-2018-20353 - June 10, 2019

An invalid read of 8 bytes due to a use-after-free vulnerability during a "NULL test" in the mg_http_get_proto_data function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.

In Cesanta Mongoose 6.13
CVE-2018-19587 6.5 - Medium - November 27, 2018

In Cesanta Mongoose 6.13, a SIGSEGV exists in the mongoose.c mg_mqtt_add_session() function.

Buffer Overflow

An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13
CVE-2018-18764 - October 29, 2018

An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13. It is a heap-based buffer over-read in a parse_mqtt getu16 call. A specially crafted MQTT SUBSCRIBE packet can cause an arbitrary out-of-bounds memory read potentially resulting in information disclosure and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13
CVE-2018-18765 - October 29, 2018

An exploitable arbitrary memory read vulnerability exists in the MQTT packet-parsing functionality of Cesanta Mongoose 6.13. It is a heap-based buffer over-read in mg_mqtt_next_subscribe_topic. A specially crafted MQTT SUBSCRIBE packet can cause an arbitrary out-of-bounds memory read potentially resulting in information disclosure and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

The mg_handle_cgi function in mongoose.c in Mongoose 6.11
CVE-2018-10945 - June 19, 2018

The mg_handle_cgi function in mongoose.c in Mongoose 6.11 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash, or NULL pointer dereference) via an HTTP request, related to the mbuf_insert function.

An exploitable use-after-free vulnerability exists in the HTTP server implementation of Cesanta Mongoose 6.8
CVE-2017-2891 9.8 - Critical - November 07, 2017

An exploitable use-after-free vulnerability exists in the HTTP server implementation of Cesanta Mongoose 6.8. An ordinary HTTP POST request with a CGI target can cause a reuse of previously freed pointer potentially resulting in remote code execution. An attacker needs to send this HTTP request over the network to trigger this vulnerability.

Dangling pointer

An exploitable arbitrary memory read vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8
CVE-2017-2892 9.8 - Critical - November 07, 2017

An exploitable arbitrary memory read vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8. A specially crafted MQTT packet can cause an arbitrary out-of-bounds memory read and write potentially resulting in information disclosure, denial of service and remote code execution. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

Integer Overflow or Wraparound

An exploitable NULL pointer dereference vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8
CVE-2017-2893 7.5 - High - November 07, 2017

An exploitable NULL pointer dereference vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8. An MQTT SUBSCRIBE packet can cause a NULL pointer dereference leading to server crash and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

NULL Pointer Dereference

An exploitable stack buffer overflow vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8
CVE-2017-2894 9.8 - Critical - November 07, 2017

An exploitable stack buffer overflow vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8. A specially crafted MQTT SUBSCRIBE packet can cause a stack buffer overflow resulting in remote code execution. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

Memory Corruption

An exploitable arbitrary memory read vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8
CVE-2017-2895 8.2 - High - November 07, 2017

An exploitable arbitrary memory read vulnerability exists in the MQTT packet parsing functionality of Cesanta Mongoose 6.8. A specially crafted MQTT SUBSCRIBE packet can cause an arbitrary out-of-bounds memory read potentially resulting in information disclosure and denial of service. An attacker needs to send a specially crafted MQTT packet over the network to trigger this vulnerability.

Out-of-bounds Read

An infinite loop programming error exists in the DNS server functionality of Cesanta Mongoose 6.8 library
CVE-2017-2909 7.5 - High - November 07, 2017

An infinite loop programming error exists in the DNS server functionality of Cesanta Mongoose 6.8 library. A specially crafted DNS request can cause an infinite loop resulting in high CPU usage and Denial Of Service. An attacker can send a packet over the network to trigger this vulnerability.

Infinite Loop

An exploitable memory corruption vulnerability exists in the Websocket protocol implementation of Cesanta Mongoose 6.8
CVE-2017-2921 9.8 - Critical - November 07, 2017

An exploitable memory corruption vulnerability exists in the Websocket protocol implementation of Cesanta Mongoose 6.8. A specially crafted websocket packet can cause an integer overflow, leading to a heap buffer overflow and resulting in denial of service and potential remote code execution. An attacker needs to send a specially crafted websocket packet over network to trigger this vulnerability.

Integer Overflow or Wraparound

An exploitable memory corruption vulnerability exists in the Websocket protocol implementation of Cesanta Mongoose 6.8
CVE-2017-2922 9.8 - Critical - November 07, 2017

An exploitable memory corruption vulnerability exists in the Websocket protocol implementation of Cesanta Mongoose 6.8. A specially crafted websocket packet can cause a buffer to be allocated while leaving stale pointers which leads to a use-after-free vulnerability which can be exploited to achieve remote code execution. An attacker needs to send a specially crafted websocket packet over the network to trigger this vulnerability.

Dangling pointer