CURL-CVE-2026-9546

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Source
https://curl.se/docs/CVE-2026-9546.html
Import Source
https://curl.se/docs/CURL-CVE-2026-9546.json
JSON Data
https://api.test.osv.dev/v1/vulns/CURL-CVE-2026-9546
Aliases
Published
2026-06-24T08:00:00Z
Modified
2026-07-07T18:35:02.773338Z
Summary
sending old referer
Details

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 
{
    "package": "curl",
    "affects": "lib",
    "last_affected": "8.20.0",
    "CWE": {
        "id": "CWE-200",
        "desc": "Exposure of Sensitive Information to an Unauthorized Actor"
    },
    "issue": "https://hackerone.com/reports/3754343",
    "severity": "Low",
    "www": "https://curl.se/docs/CVE-2026-9546.html",
    "URL": "https://curl.se/docs/CVE-2026-9546.json"
}
References
Credits
    • renjian on hackerone - FINDER
    • Daniel Stenberg - REMEDIATION_DEVELOPER

Affected packages

Git / github.com/curl/curl.git

Affected ranges

Type
SEMVER
Events
Introduced
8.18.0
Fixed
8.21.0
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

Database specific

vanir_signatures 
[
    {
        "id": "CURL-CVE-2026-9546-7ba9ca43",
        "digest": {
            "line_hashes": [
                "329802710635362475633966257142929289229",
                "59722172210655117825890418870938329781",
                "183831522990858182837473479172905867047",
                "304554302798540308152858876043779062238"
            ],
            "threshold": 0.9
        },
        "target": {
            "file": "lib/transfer.c"
        },
        "signature_version": "v1",
        "source": "https://github.com/curl/curl.git/commit/862e8a74a84478d82973471b4f49dc2746c1780e",
        "deprecated": false,
        "signature_type": "Line"
    },
    {
        "id": "CURL-CVE-2026-9546-93bc1aa3",
        "digest": {
            "length": 3790.0,
            "function_hash": "192731219037552860576466850254657292841"
        },
        "target": {
            "function": "Curl_pretransfer",
            "file": "lib/transfer.c"
        },
        "signature_version": "v1",
        "source": "https://github.com/curl/curl.git/commit/862e8a74a84478d82973471b4f49dc2746c1780e",
        "deprecated": false,
        "signature_type": "Function"
    }
]
source 
"https://curl.se/docs/CURL-CVE-2026-9546.json"
vanir_signatures_modified 
"2026-07-07T18:35:02Z"