CVE & CISA-KEV Catalog

CVE-2026-4873

MEDIUM
5.9
CVSS v3
NVD

Description

A vulnerability exists where a connection requiring TLS incorrectly reuses an existing unencrypted connection from the same connection pool. If an initial transfer is made in clear-text (via IMAP, SMTP, or POP3), a subsequent request to that same host bypasses the TLS requirement and instead transmit data unencrypted.

CWE-295Improper Certificate ValidationCWE-319

How to fix

Remediation Available
curlDebian
Fixed in:8.20.0~rc2-1CVE-2026-4873
curlRocky
Fixed in:main@x86_64RHSA-2026:12916
Fixed in:main@aarch64RHSA-2026:12916
Fixed in:main@srcRHSA-2026:12916
curlRed Hat / RHEL
Fixed in:main@aarch64RHSA-2026:12916
Fixed in:main@srcRHSA-2026:12916
Fixed in:main@x86_64RHSA-2026:12916
curlUbuntu
Fixed in:7.81.0-1ubuntu1.24USN-8227-1
Fixed in:8.5.0-2ubuntu10.9USN-8227-1
Fixed in:8.14.1-2ubuntu1.3USN-8227-1
libcurl3-gnutlsUbuntu
Fixed in:7.81.0-1ubuntu1.24USN-8227-1
libcurl3-nssUbuntu
Fixed in:7.81.0-1ubuntu1.24USN-8227-1
libcurl3t64-gnutlsUbuntu
Fixed in:8.5.0-2ubuntu10.9USN-8227-1
Fixed in:8.14.1-2ubuntu1.3USN-8227-1
libcurl4Ubuntu
Fixed in:7.81.0-1ubuntu1.24USN-8227-1
libcurl4t64Ubuntu
Fixed in:8.5.0-2ubuntu10.9USN-8227-1
Fixed in:8.14.1-2ubuntu1.3USN-8227-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityNone
AvailabilityNone

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

Exploit Intelligence

0.33%probability of exploitation in 30 days
25thpercentile

Low risk: more likely to be exploited than 25% of all known CVEs.

References

Vendor Advisory1
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CVE-2026-4873 severity badge

Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-14.