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CVE Record

CVE-2026-5545: wrong reuse of HTTP Negotiate connection

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...

MediumCVSS 6.5Not KEV-listedUpdated
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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
6.5CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N2.24.2CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

6.5Medium
CVSS 3.1 vector shape for CVE-2026-5545Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

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  3. CVE updatedCVE Program

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ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
curlcurl7.10.6, 8.15.0, 8.17.0unaffected
curlcurle56ae1426cb7a0a4a427cf8d6099a821fdaae428unaffected
curlcurl8.19.0, 8.18.0, 8.17.0, 8.16.0, 8.15.0, 8.14.1, 8.14.0, 8.13.0, 8.12.1, 8.12.0, 8.11.1, 8.11.0, 8.10.1, 8.10.0, 8.9.1, 8.9.0, 8.8.0, 8.7.1, 8.7.0, 8.6.0, 8.5.0, 8.4.0, 8.3.0, 8.2.1, 8.2.0, 8.1.2, 8.1.1, 8.1.0, 8.0.1, 8.0.0, 7.88.1, 7.88.0, 7.87.0, 7.86.0, 7.85.0, 7.84.0, 7.83.1, 7.83.0, 7.82.0, 7.81.0, 7.80.0, 7.79.1, 7.79.0, 7.78.0, 7.77.0, 7.76.1, 7.76.0, 7.75.0, 7.74.0, 7.73.0, 7.72.0, 7.71.1, 7.71.0, 7.70.0, 7.69.1, 7.69.0, 7.68.0, 7.67.0, 7.66.0, 7.65.3, 7.65.2, 7.65.1, 7.65.0, 7.64.1, 7.64.0, 7.63.0, 7.62.0, 7.61.1, 7.61.0, 7.60.0, 7.59.0, 7.58.0, 7.57.0, 7.56.1, 7.56.0, 7.55.1, 7.55.0, 7.54.1, 7.54.0, 7.53.1, 7.53.0, 7.52.1, 7.52.0, 7.51.0, 7.50.3, 7.50.2, 7.50.1, 7.50.0, 7.49.1, 7.49.0, 7.48.0, 7.47.1, 7.47.0, 7.46.0, 7.45.0, 7.44.0, 7.43.0, 7.42.1, 7.42.0, 7.41.0, 7.40.0, 7.39.0, 7.38.0, 7.37.1, 7.37.0, 7.36.0, 7.35.0, 7.34.0, 7.33.0, 7.32.0, 7.31.0, 7.30.0, 7.29.0, 7.28.1, 7.28.0, 7.27.0, 7.26.0, 7.25.0, 7.24.0, 7.23.1, 7.23.0, 7.22.0, 7.21.7, 7.21.6, 7.21.5, 7.21.4, 7.21.3, 7.21.2, 7.21.1, 7.21.0, 7.20.1, 7.20.0, 7.19.7, 7.19.6, 7.19.5, 7.19.4, 7.19.3, 7.19.2, 7.19.1, 7.19.0, 7.18.2, 7.18.1, 7.18.0, 7.17.1, 7.17.0, 7.16.4, 7.16.3, 7.16.2, 7.16.1, 7.16.0, 7.15.5, 7.15.4, 7.15.3, 7.15.2, 7.15.1, 7.15.0, 7.14.1, 7.14.0, 7.13.2, 7.13.1, 7.13.0, 7.12.3, 7.12.2, 7.12.1, 7.12.0, 7.11.2, 7.11.1, 7.11.0, 7.10.8, 7.10.7, 7.10.6unaffected
Weakness

CWE details

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Authentication Bypass by Primary Weakness

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