CVE-2021-31875

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Source
https://cve.org/CVERecord?id=CVE-2021-31875
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31875.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2021-31875
Published
2021-04-29T02:15:08Z
Modified
2026-07-08T22:15:02Z
Severity
  • 9.8 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
[none]
Details

In mjs_json.c in Cesanta MongooseOS mJS 1.26, a maliciously formed JSON string can trigger an off-by-one heap-based buffer overflow in mjs_json_parse, which can potentially lead to redirection of control flow. NOTE: the original reporter disputes the significance of this finding because "there isn’t very much of an opportunity to exploit this reliably for an information leak, so there isn’t any real security impact."

References

Affected packages

Git / github.com/418sec/mjs

Affected ranges

Type
GIT
Repo
https://github.com/418sec/mjs
Events
Introduced
30aa0f84dbb274afdd95006ed18431e131654cac
Last Affected
30aa0f84dbb274afdd95006ed18431e131654cac
Database specific
Show details 
{
    "cpe": "cpe:2.3:a:cesanta:mongooseos_mjs:1.26:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "1.26"
        },
        {
            "last_affected": "1.26"
        }
    ],
    "source": "CPE_STRING"
}

Affected versions

1.*
1.26

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31875.json"

Git / github.com/cesanta/mjs

Affected ranges

Type
GIT
Repo
https://github.com/cesanta/mjs
Events
Introduced
30aa0f84dbb274afdd95006ed18431e131654cac
Last Affected
30aa0f84dbb274afdd95006ed18431e131654cac
Fixed
30aa0f84dbb274afdd95006ed18431e131654cac
Database specific
Show details 
{
    "cpe": "cpe:2.3:a:cesanta:mongooseos_mjs:1.26:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "1.26"
        },
        {
            "last_affected": "1.26"
        }
    ],
    "source": [
        "CPE_STRING",
        "REFERENCES"
    ]
}

Affected versions

1.*
1.26

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-31875.json"
vanir_signatures 
[
    {
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "234456157171672009667012020005863685987",
                "146345927612699616111074413700893716313",
                "108905283697329949653992095110269968398",
                "40928701320816293082107573540797344185",
                "16737667361413382403951905663352361970",
                "32490330477822729405061052842574627060",
                "164173215868758275743162668968896081187",
                "336220235712481336989938226589175284337",
                "320868728181603703685665517682974328720",
                "27893539343358266705685645107797522834"
            ],
            "threshold": 0.9
        },
        "id": "CVE-2021-31875-6caf7cb9",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/cesanta/mjs/commit/30aa0f84dbb274afdd95006ed18431e131654cac",
        "target": {
            "file": "common/cs_varint.c"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "function_hash": "291219462004385368167517558065082996591",
            "length": 389
        },
        "id": "CVE-2021-31875-7753ab29",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/cesanta/mjs/commit/30aa0f84dbb274afdd95006ed18431e131654cac",
        "target": {
            "file": "mjs.c",
            "function": "cs_varint_decode"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "function_hash": "291219462004385368167517558065082996591",
            "length": 389
        },
        "id": "CVE-2021-31875-789e4ca9",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/cesanta/mjs/commit/30aa0f84dbb274afdd95006ed18431e131654cac",
        "target": {
            "file": "common/cs_varint.c",
            "function": "cs_varint_decode"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "234456157171672009667012020005863685987",
                "146345927612699616111074413700893716313",
                "108905283697329949653992095110269968398",
                "40928701320816293082107573540797344185",
                "16737667361413382403951905663352361970",
                "32490330477822729405061052842574627060",
                "164173215868758275743162668968896081187",
                "336220235712481336989938226589175284337",
                "320868728181603703685665517682974328720",
                "27893539343358266705685645107797522834"
            ],
            "threshold": 0.9
        },
        "id": "CVE-2021-31875-ebec0f7c",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/cesanta/mjs/commit/30aa0f84dbb274afdd95006ed18431e131654cac",
        "target": {
            "file": "mjs.c"
        }
    }
]
vanir_signatures_modified 
"2026-07-08T22:15:02Z"