CVE-2026-9546

A vulnerability in libcurl caused the HTTP Referer: header to persist even when explicitly cleared. While the documentation states that passing NULL to CURLOPT_REFERER suppresses the header, the option failed to clear the internal state. As a result, the previous referrer string was erroneously reused and sent in subsequent requests, potentially leaking sensitive information to unintended servers.

Database specific

{
    "cna_assigner": "curl",
    "cwe_ids": [
        "CWE-200"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9546.json"
}

References

Affected packages

Git / github.com/curl/curl

Affected ranges

Type

GIT

Repo

https://github.com/curl/curl

Events

Introduced

2eebc58c4b8d68c98c8344381a9f6df4cca838fd

Fixed

68720b4837284335b2d63cb358f8f6ce65f5bc55

Database specific

Show details

{
    "cpe": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*",
    "extracted_events": [
        {
            "introduced": "8.18.0"
        },
        {
            "fixed": "8.21.0"
        }
    ],
    "source": "CPE_RANGE"
}

Type: GIT
Repo: https://github.com/curl/curl.git
Events: Introduced

2cb868242dc2ac9cd52ee64987ef51d5964a56f9

Fixed

862e8a74a84478d82973471b4f49dc2746c1780e

Affected versions

8.*

8.18.0

8.19.0

8.20.0

Other

curl-8_18_0

curl-8_19_0

curl-8_20_0

rc-8_18_0-1

rc-8_18_0-2

rc-8_18_0-3

rc-8_19_0-1

rc-8_19_0-2

rc-8_19_0-3

rc-8_20_0-1

rc-8_20_0-2

rc-8_20_0-3

rc-8_21_0-1

rc-8_21_0-2

rc-8_21_0-3

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-9546.json"

vanir_signatures

[
    {
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "329802710635362475633966257142929289229",
                "59722172210655117825890418870938329781",
                "183831522990858182837473479172905867047",
                "304554302798540308152858876043779062238"
            ],
            "threshold": 0.9
        },
        "id": "CVE-2026-9546-7ba9ca43",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/curl/curl.git/commit/862e8a74a84478d82973471b4f49dc2746c1780e",
        "target": {
            "file": "lib/transfer.c"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "function_hash": "192731219037552860576466850254657292841",
            "length": 3790
        },
        "id": "CVE-2026-9546-93bc1aa3",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/curl/curl.git/commit/862e8a74a84478d82973471b4f49dc2746c1780e",
        "target": {
            "file": "lib/transfer.c",
            "function": "Curl_pretransfer"
        }
    }
]

vanir_signatures_modified

"2026-10-08T07:15:45Z"