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Vulnerability record · CVE-2018-20355 · published 10 June 2019

CVE-2018-20355: Cesanta mongoose use after free vulnerability

Cesanta · Mongoose

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.

9.8 CVSS 3.0 Critical EPSS 3.6% · top 11.0% CWE-416 · Use after free
9.8CVSS 3.0 base score, v2 7.5
3.6%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/insi2304/mongoose-6.13-fuzz/blob/master/Simplest_Web_Server_Use_After_Free-mg_http_free_proto_data_cg ExploitThird Party Advisory
https://github.com/insi2304/mongoose-6.13-fuzz/blob/master/Simplest_Web_Server_Use_After_Free-mg_http_free_proto_data_cg ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2024-42383Cesanta mongoose vulnerabilityUse 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 dedic…EPSS 0.27%9.8CVE-2020-25756Cesanta mongoose classic buffer overflow vulnerabilityA 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 h…EPSS 1.6%9.8CVE-2019-19307Cesanta mongoose out-of-bounds read vulnerabilityAn 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 …EPSS 42%9.8CVE-2019-12951Cesanta mongoose out-of-bounds write vulnerabilityAn issue was discovered in Mongoose before 6.15. The parse_mqtt() function in mg_mqtt.c has a critical heap-based buffer overflow.EPSS 2.0%9.8CVE-2018-20353Cesanta mongoose use after free vulnerabilityAn 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…EPSS 3.6%9.8CVE-2018-20354Cesanta mongoose use after free vulnerabilityAn 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 Mo…EPSS 3.6%9.8CVE-2018-20356Cesanta mongoose use after free vulnerabilityAn 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 E…EPSS 3.6%9.8CVE-2017-2921Cesanta mongoose integer overflow vulnerabilityAn exploitable memory corruption vulnerability exists in the Websocket protocol implementation of Cesanta Mongoose 6.8. A specially crafted websocket…EPSS 2.4%

Source: NIST National Vulnerability Database (record CVE-2018-20355), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.