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...

The remote SUSE Linux SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:1940-1 advisory.

    Security issues fixed:

    - CVE-2026-4873: connection reuse ignores TLS requirement (bsc#1262631).
    - CVE-2026-5545: wrong reuse of HTTP Negotiate connection (bsc#1262632).
    - CVE-2026-6253: proxy credentials leak over redirect-to proxy (bsc#1262635).
    - CVE-2026-6276: stale custom cookie host causes cookie leak (bsc#1262636).
    - CVE-2026-6429: netrc credential leak with reused proxy connection (bsc#1262638).

    Other updates and bugfixes:

    - sws: prevent 'connection monitor' to say disconnect twice (bsc#1259362).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has packages installed that are affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:1717-1 advisory.

    Security issues fixed:

    - CVE-2026-4873: connection reuse ignores TLS requirement (bsc#1262631).
    - CVE-2026-5545: wrong reuse of HTTP Negotiate connection (bsc#1262632).
    - CVE-2026-6253: proxy credentials leak over redirect-to proxy (bsc#1262635).
    - CVE-2026-6276: stale custom cookie host causes cookie leak (bsc#1262636).
    - CVE-2026-6429: netrc credential leak with reused proxy connection (bsc#1262638).

    Other updates and bugfixes:

    - sws: prevent 'connection monitor' to say disconnect twice (bsc#1259362).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

An update of the curl package has been released.

The remote Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8227-1 advisory.

    It was discovered that curl incorrectly reused non-TLS connections when TLS was required in some STARTTLS     configurations. A remote attacker could possibly use this issue to obtain sensitive information.
    (CVE-2026-4873)

    It was discovered that curl incorrectly reused certain HTTP Negotiate connections. A remote attacker could     possibly use this issue to obtain sensitive information. (CVE-2026-5545)

    It was discovered that curl incorrectly reused certain SMB connections. A remote attacker could possibly     use this issue to obtain sensitive information. (CVE-2026-5773)

    It was discovered that curl could leak proxy credentials when handling redirects in some configurations. A     remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6253)

    It was discovered that curl could leak cookies because of stale custom cookie host handling in some     requests. A remote attacker could possibly use this issue to obtain sensitive information. (CVE-2026-6276)

    It was discovered that curl could leak .netrc credentials when reusing proxy connections in some     situations. A remote attacker could possibly use this issue to obtain sensitive information.
    (CVE-2026-6429)

    It was discovered that curl could leak Digest authentication state when switching proxies in some     situations. A remote attacker could possibly use this issue to obtain sensitive information.
    (CVE-2026-7168)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of curl installed on the remote host is 7.10.6 prior to 8.20.0. It is, therefore, affected by an authentication bypass vulnerability:

  - 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. When an application     first authenticates to a server using Negotiate with one set of credentials and then makes a subsequent     request with different credentials, libcurl may inappropriately reuse the earlier connection, resulting     in the new request being sent over a connection still authenticated for the original user.
    (CVE-2026-5545)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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... (CVE-2026-5545)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
315269	SUSE SLES15 Security Update : curl (SUSE-SU-2026:1940-1)	Nessus	SuSE Local Security Checks	medium
313680	SUSE SLED15 / SLES15 Security Update : curl (SUSE-SU-2026:1717-1)	Nessus	SuSE Local Security Checks	medium
313013	Photon OS 5.0: Curl PHSA-2026-5.0-0838	Nessus	PhotonOS Local Security Checks	high
313011	Photon OS 4.0: Curl PHSA-2026-4.0-1007	Nessus	PhotonOS Local Security Checks	high
312298	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : curl vulnerabilities (USN-8227-1)	Nessus	Ubuntu Local Security Checks	high
311425	Curl 7.10.6 < 8.20.0 Wrong Reuse of HTTP Negotiate Connection	Nessus	Misc.	medium
311003	Linux Distros Unpatched Vulnerability : CVE-2026-5545	Nessus	Misc.	medium

Detections

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CVE-2026-5545

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Tenable Plugins

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medium