wrong reuse of HTTP Negotiate connection_CVE-2026-5545

6.5 / 10

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

Description

libcurl might in some circumstances reuse the wrong connection when asked to
do an authenticated HTTP(S) request after a Negotiate-authenticated one, when
both use the same host.

libcurl features a pool of recent connections so that subsequent requests can
reuse an existing connection to avoid overhead.

When reusing a connection a range of criteria must be met. Due to a logical
error in the code, a request that was issued by an application could
wrongfully reuse an existing connection to the same server that was
authenticated using different credentials.

An application that first uses Negotiate authentication to a server with
`user1:password1` and then does another operation to the same server asking
for any authentication method but for `user2:password2` (while the previous
connection is still alive) - the second request gets confused and wrongly
reuses the same connection and sends the new request over that connection
thinking it uses a mix of user1's and user2's credentials when it is in fact
still using the connection authenticated for user1...

Basic Information

ID CVE-2026-5545

Source curl

Published May 13, 2026 at 08:27

Modified May 13, 2026 at 17:46

Affected Product

Vendor curl

Product curl

Version 8.19.0

Affected Versions curl curl 8.19.0
curl curl 8.18.0
curl curl 8.17.0
curl curl 8.16.0
curl curl 8.15.0
curl curl 8.14.1
curl curl 8.14.0
curl curl 8.13.0
curl curl 8.12.1
curl curl 8.12.0
curl curl 8.11.1
curl curl 8.11.0
curl curl 8.10.1
curl curl 8.10.0
curl curl 8.9.1
curl curl 8.9.0
curl curl 8.8.0
curl curl 8.7.1
curl curl 8.7.0
curl curl 8.6.0
curl curl 8.5.0
curl curl 8.4.0
curl curl 8.3.0
curl curl 8.2.1
curl curl 8.2.0
curl curl 8.1.2
curl curl 8.1.1
curl curl 8.1.0
curl curl 8.0.1
curl curl 8.0.0
curl curl 7.88.1
curl curl 7.88.0
curl curl 7.87.0
curl curl 7.86.0
curl curl 7.85.0
curl curl 7.84.0
curl curl 7.83.1
curl curl 7.83.0
curl curl 7.82.0
curl curl 7.81.0
curl curl 7.80.0
curl curl 7.79.1
curl curl 7.79.0
curl curl 7.78.0
curl curl 7.77.0
curl curl 7.76.1
curl curl 7.76.0
curl curl 7.75.0
curl curl 7.74.0
curl curl 7.73.0
curl curl 7.72.0
curl curl 7.71.1
curl curl 7.71.0
curl curl 7.70.0
curl curl 7.69.1
curl curl 7.69.0
curl curl 7.68.0
curl curl 7.67.0
curl curl 7.66.0
curl curl 7.65.3
curl curl 7.65.2
curl curl 7.65.1
curl curl 7.65.0
curl curl 7.64.1
curl curl 7.64.0
curl curl 7.63.0
curl curl 7.62.0
curl curl 7.61.1
curl curl 7.61.0
curl curl 7.60.0
curl curl 7.59.0
curl curl 7.58.0
curl curl 7.57.0
curl curl 7.56.1
curl curl 7.56.0
curl curl 7.55.1
curl curl 7.55.0
curl curl 7.54.1
curl curl 7.54.0
curl curl 7.53.1
curl curl 7.53.0
curl curl 7.52.1
curl curl 7.52.0
curl curl 7.51.0
curl curl 7.50.3
curl curl 7.50.2
curl curl 7.50.1
curl curl 7.50.0
curl curl 7.49.1
curl curl 7.49.0
curl curl 7.48.0
curl curl 7.47.1
curl curl 7.47.0
curl curl 7.46.0
curl curl 7.45.0
curl curl 7.44.0
curl curl 7.43.0
curl curl 7.42.1
curl curl 7.42.0
curl curl 7.41.0
curl curl 7.40.0
curl curl 7.39.0
curl curl 7.38.0
curl curl 7.37.1
curl curl 7.37.0
curl curl 7.36.0
curl curl 7.35.0
curl curl 7.34.0
curl curl 7.33.0
curl curl 7.32.0
curl curl 7.31.0
curl curl 7.30.0
curl curl 7.29.0
curl curl 7.28.1
curl curl 7.28.0
curl curl 7.27.0
curl curl 7.26.0
curl curl 7.25.0
curl curl 7.24.0
curl curl 7.23.1
curl curl 7.23.0
curl curl 7.22.0
curl curl 7.21.7
curl curl 7.21.6
curl curl 7.21.5
curl curl 7.21.4
curl curl 7.21.3
curl curl 7.21.2
curl curl 7.21.1
curl curl 7.21.0
curl curl 7.20.1
curl curl 7.20.0
curl curl 7.19.7
curl curl 7.19.6
curl curl 7.19.5
curl curl 7.19.4
curl curl 7.19.3
curl curl 7.19.2
curl curl 7.19.1
curl curl 7.19.0
curl curl 7.18.2
curl curl 7.18.1
curl curl 7.18.0
curl curl 7.17.1
curl curl 7.17.0
curl curl 7.16.4
curl curl 7.16.3
curl curl 7.16.2
curl curl 7.16.1
curl curl 7.16.0
curl curl 7.15.5
curl curl 7.15.4
curl curl 7.15.3
curl curl 7.15.2
curl curl 7.15.1
curl curl 7.15.0
curl curl 7.14.1
curl curl 7.14.0
curl curl 7.13.2
curl curl 7.13.1
curl curl 7.13.0
curl curl 7.12.3
curl curl 7.12.2
curl curl 7.12.1
curl curl 7.12.0
curl curl 7.11.2
curl curl 7.11.1
curl curl 7.11.0
curl curl 7.10.8
curl curl 7.10.7
curl curl 7.10.6

References

{
    "lastseen": "",
    "description": "libcurl might in some circumstances reuse the wrong connection when asked to\ndo an authenticated HTTP(S) request after a Negotiate-authenticated one, when\nboth use the same host.\n\nlibcurl features a pool of recent connections so that subsequent requests can\nreuse an existing connection to avoid overhead.\n\nWhen reusing a connection a range of criteria must be met. Due to a logical\nerror in the code, a request that was issued by an application could\nwrongfully reuse an existing connection to the same server that was\nauthenticated using different credentials.\n\nAn application that first uses Negotiate authentication to a server with\n`user1:password1` and then does another operation to the same server asking\nfor any authentication method but for `user2:password2` (while the previous\nconnection is still alive) - the second request gets confused and wrongly\nreuses the same connection and sends the new request over that connection\nthinking it uses a mix of user1's and user2's credentials when it is in fact\nstill using the connection authenticated for user1...",
    "published": "2026-05-13T08:27:26.065Z",
    "modified": "2026-05-13T17:46:40.830Z",
    "type": "cve",
    "title": "wrong reuse of HTTP Negotiate connection",
    "source": "curl",
    "references": "https://curl.se/docs/CVE-2026-5545.json\nhttps://curl.se/docs/CVE-2026-5545.html\nhttps://hackerone.com/reports/3642555",
    "id": "CVE-2026-5545",
    "bulletinFamily": "",
    "cwe": null,
    "cvelist": null,
    "sourceData": "curl curl 8.19.0\ncurl curl 8.18.0\ncurl curl 8.17.0\ncurl curl 8.16.0\ncurl curl 8.15.0\ncurl curl 8.14.1\ncurl curl 8.14.0\ncurl curl 8.13.0\ncurl curl 8.12.1\ncurl curl 8.12.0\ncurl curl 8.11.1\ncurl curl 8.11.0\ncurl curl 8.10.1\ncurl curl 8.10.0\ncurl curl 8.9.1\ncurl curl 8.9.0\ncurl curl 8.8.0\ncurl curl 8.7.1\ncurl curl 8.7.0\ncurl curl 8.6.0\ncurl curl 8.5.0\ncurl curl 8.4.0\ncurl curl 8.3.0\ncurl curl 8.2.1\ncurl curl 8.2.0\ncurl curl 8.1.2\ncurl curl 8.1.1\ncurl curl 8.1.0\ncurl curl 8.0.1\ncurl curl 8.0.0\ncurl curl 7.88.1\ncurl curl 7.88.0\ncurl curl 7.87.0\ncurl curl 7.86.0\ncurl curl 7.85.0\ncurl curl 7.84.0\ncurl curl 7.83.1\ncurl curl 7.83.0\ncurl curl 7.82.0\ncurl curl 7.81.0\ncurl curl 7.80.0\ncurl curl 7.79.1\ncurl curl 7.79.0\ncurl curl 7.78.0\ncurl curl 7.77.0\ncurl curl 7.76.1\ncurl curl 7.76.0\ncurl curl 7.75.0\ncurl curl 7.74.0\ncurl curl 7.73.0\ncurl curl 7.72.0\ncurl curl 7.71.1\ncurl curl 7.71.0\ncurl curl 7.70.0\ncurl curl 7.69.1\ncurl curl 7.69.0\ncurl curl 7.68.0\ncurl curl 7.67.0\ncurl curl 7.66.0\ncurl curl 7.65.3\ncurl curl 7.65.2\ncurl curl 7.65.1\ncurl curl 7.65.0\ncurl curl 7.64.1\ncurl curl 7.64.0\ncurl curl 7.63.0\ncurl curl 7.62.0\ncurl curl 7.61.1\ncurl curl 7.61.0\ncurl curl 7.60.0\ncurl curl 7.59.0\ncurl curl 7.58.0\ncurl curl 7.57.0\ncurl curl 7.56.1\ncurl curl 7.56.0\ncurl curl 7.55.1\ncurl curl 7.55.0\ncurl curl 7.54.1\ncurl curl 7.54.0\ncurl curl 7.53.1\ncurl curl 7.53.0\ncurl curl 7.52.1\ncurl curl 7.52.0\ncurl curl 7.51.0\ncurl curl 7.50.3\ncurl curl 7.50.2\ncurl curl 7.50.1\ncurl curl 7.50.0\ncurl curl 7.49.1\ncurl curl 7.49.0\ncurl curl 7.48.0\ncurl curl 7.47.1\ncurl curl 7.47.0\ncurl curl 7.46.0\ncurl curl 7.45.0\ncurl curl 7.44.0\ncurl curl 7.43.0\ncurl curl 7.42.1\ncurl curl 7.42.0\ncurl curl 7.41.0\ncurl curl 7.40.0\ncurl curl 7.39.0\ncurl curl 7.38.0\ncurl curl 7.37.1\ncurl curl 7.37.0\ncurl curl 7.36.0\ncurl curl 7.35.0\ncurl curl 7.34.0\ncurl curl 7.33.0\ncurl curl 7.32.0\ncurl curl 7.31.0\ncurl curl 7.30.0\ncurl curl 7.29.0\ncurl curl 7.28.1\ncurl curl 7.28.0\ncurl curl 7.27.0\ncurl curl 7.26.0\ncurl curl 7.25.0\ncurl curl 7.24.0\ncurl curl 7.23.1\ncurl curl 7.23.0\ncurl curl 7.22.0\ncurl curl 7.21.7\ncurl curl 7.21.6\ncurl curl 7.21.5\ncurl curl 7.21.4\ncurl curl 7.21.3\ncurl curl 7.21.2\ncurl curl 7.21.1\ncurl curl 7.21.0\ncurl curl 7.20.1\ncurl curl 7.20.0\ncurl curl 7.19.7\ncurl curl 7.19.6\ncurl curl 7.19.5\ncurl curl 7.19.4\ncurl curl 7.19.3\ncurl curl 7.19.2\ncurl curl 7.19.1\ncurl curl 7.19.0\ncurl curl 7.18.2\ncurl curl 7.18.1\ncurl curl 7.18.0\ncurl curl 7.17.1\ncurl curl 7.17.0\ncurl curl 7.16.4\ncurl curl 7.16.3\ncurl curl 7.16.2\ncurl curl 7.16.1\ncurl curl 7.16.0\ncurl curl 7.15.5\ncurl curl 7.15.4\ncurl curl 7.15.3\ncurl curl 7.15.2\ncurl curl 7.15.1\ncurl curl 7.15.0\ncurl curl 7.14.1\ncurl curl 7.14.0\ncurl curl 7.13.2\ncurl curl 7.13.1\ncurl curl 7.13.0\ncurl curl 7.12.3\ncurl curl 7.12.2\ncurl curl 7.12.1\ncurl curl 7.12.0\ncurl curl 7.11.2\ncurl curl 7.11.1\ncurl curl 7.11.0\ncurl curl 7.10.8\ncurl curl 7.10.7\ncurl curl 7.10.6",
    "sourceHref": "",
    "cvss": {
        "score": 6.5,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "curl",
    "version": "8.19.0",
    "vendor": "curl",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}

Description

Basic Information

Affected Product

References

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