CVE-2026-73251

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Source
https://cve.org/CVERecord?id=CVE-2026-73251
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-73251.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-73251
Aliases
  • GHSA-qj6j-2692-v2r8
Downstream
Published
2026-08-20T17:34:50Z
Modified
2026-09-11T08:40:04Z
Severity
  • 9.3 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Mongoose Built-in TLS: CA-bundle certificate chain accepted without any signature verification
Details

Mongoose is an embedded web server and network library. Prior to 7.23, a network attacker can impersonate a TLS server to a Mongoose client configured with a multi-certificate CA bundle. In src/tls_builtin.c, the mg_tls_init() function stores the bundle in tls->ca_bundle_der while tls->ca_der.len remains zero, and mg_tls_recv_cert() uses tls_bundle_find() to accept a Common Name match without calling mg_tls_verify_cert_signature(). A forged self-signed certificate can therefore satisfy hostname and CertificateVerify checks and enable interception, credential disclosure, traffic modification, and malicious responses. This issue is fixed in version 7.23.

Database specific 
{
    "cna_assigner":  "GitHub_M",
    "cwe_ids":  [
        "CWE-295"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73251.json"
}
References

Affected packages

Git / github.com/cesanta/mongoose

Affected ranges

Type
GIT
Repo
https://github.com/cesanta/mongoose
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
2988bc9df3a5efc9539471cb7455975fa25df483
Fixed
02bdbb9ed6f0a8f7c42228c6e7cb35d748b60551
Database specific
Show details 
{
    "extracted_events":  [
        {
            "introduced":  "0"
        },
        {
            "fixed":  "7.23"
        }
    ],
    "source":  [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

3.*
3.2
3.3
3.4
3.5
3.6
3.7
3.8
4.*
4.0
4.1
5.*
5.0
5.1
5.2
5.3
5.4
5.5
5.5_20140120
5.6
6.*
6.0
6.1
6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
6.18
6.2
6.3
6.4
6.5
6.6
6.7
6.9
7.*
7.0
7.1
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.2
7.20
7.21
7.22
7.3
7.4
7.5
7.6
7.7
7.8

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-73251.json"
vanir_signatures 
[
    {
        "deprecated":  false,
        "digest":  {
            "line_hashes":  [
                "280880759204458332186591428807639899707",
                "91784847098628061190181036714616550317",
                "260324905700960565902262748823032487472",
                "1462060790025201554329754208352907614"
            ],
            "threshold":  0.9
        },
        "id":  "CVE-2026-73251-4e9d2e62",
        "signature_type":  "Line",
        "signature_version":  "v1",
        "source":  "https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483",
        "target":  {
            "file":  "mongoose.c"
        }
    },
    {
        "deprecated":  false,
        "digest":  {
            "function_hash":  "179946136510036810370347435467022032985",
            "length":  4038
        },
        "id":  "CVE-2026-73251-7aa16f5b",
        "signature_type":  "Function",
        "signature_version":  "v1",
        "source":  "https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483",
        "target":  {
            "file":  "src/tls_builtin.c",
            "function":  "mg_tls_recv_cert"
        }
    },
    {
        "deprecated":  false,
        "digest":  {
            "function_hash":  "179946136510036810370347435467022032985",
            "length":  4038
        },
        "id":  "CVE-2026-73251-b716628b",
        "signature_type":  "Function",
        "signature_version":  "v1",
        "source":  "https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483",
        "target":  {
            "file":  "mongoose.c",
            "function":  "mg_tls_recv_cert"
        }
    },
    {
        "deprecated":  false,
        "digest":  {
            "line_hashes":  [
                "280880759204458332186591428807639899707",
                "91784847098628061190181036714616550317",
                "260324905700960565902262748823032487472",
                "1462060790025201554329754208352907614"
            ],
            "threshold":  0.9
        },
        "id":  "CVE-2026-73251-d2542a77",
        "signature_type":  "Line",
        "signature_version":  "v1",
        "source":  "https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483",
        "target":  {
            "file":  "src/tls_builtin.c"
        }
    }
]
vanir_signatures_modified 
"2026-09-11T08:40:04Z"