CVE-2026-73261

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Source

https://cve.org/CVERecord?id=CVE-2026-73261

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73261.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-73261

Aliases

GHSA-3fmr-92g4-wchx

Downstream

Published

2026-10-14T18:25:41Z

Modified

2026-10-31T07:10:20Z

Severity

7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator

Summary

Mongoose: handle_opt() missing opts[1] > len check — 1-byte OOB read corrupts TCP MSS, silences mg_send() per connection

Details

Mongoose is an embedded web server and network library. Prior to 7.23, the built-in TCP/IP stack enabled by MG_ENABLE_TCPIP in src/net_builtin.c does not reject a TCP option whose declared opts[1] length exceeds the remaining option bytes. In handle_opt(), a NOP followed by a truncated MSS option causes opts[3] to be read outside the declared options area and used as the low byte of dmss. An unauthenticated remote peer can corrupt the per-connection MSS value so later mg_send() calls transmit truncated or zero-length application payloads while the TCP connection otherwise appears healthy. This issue is fixed in version 7.23.

Database specific

{
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-125",
        "CWE-20"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73261.json"
}

References

Affected packages

Git / github.com/cesanta/mongoose

Affected ranges

Type

GIT

Repo

https://github.com/cesanta/mongoose

Events

Introduced

Fixed

02bdbb9ed6f0a8f7c42228c6e7cb35d748b60551

Fixed

cc7c6d2d18c28fcc6d085633dddd88402946140a

Database specific

Show details

{
    "extracted_events": [
        {
            "range": [
                {
                    "introduced": "0"
                },
                {
                    "fixed": "7.23"
                }
            ],
            "source": "AFFECTED_FIELD",
            "strategy": "StringRangeExpression"
        },
        {
            "range": [
                {
                    "fixed": "cc7c6d2d18c28fcc6d085633dddd88402946140a"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "original_tag": "7.23",
            "range": [
                {
                    "fixed": "02bdbb9ed6f0a8f7c42228c6e7cb35d748b60551"
                }
            ],
            "source": "REFERENCES_TAG"
        }
    ]
}

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/cve-osv-conversion/osv-output/CVE-2026-73261.json"

vanir_signatures

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vanir_signatures_modified

"2026-10-31T07:10:20Z"