How severe is CVE-2026-4873?

CVE-2026-4873 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-4873 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4873?

CVE-2026-4873 affects Haxx Curl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4873?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4873 have an EU (EUVD) identifier?

Yes. CVE-2026-4873 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29922.

When was CVE-2026-4873 published?

CVE-2026-4873 was published on 2026-05-13 and last updated on 2026-06-17.

CVE-2026-4873

CVE-2026-4873 is a medium-severity vulnerability in Haxx Curl with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (25th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-29922
Weakness: CWE-295
Affected product: Haxx Curl
Published: 2026-05-13
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-4873?: 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.
How severe is CVE-2026-4873?: CVE-2026-4873 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-4873 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (25th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4873?: CVE-2026-4873 affects Haxx Curl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4873?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4873 have an EU (EUVD) identifier?: Yes. CVE-2026-4873 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-29922.
When was CVE-2026-4873 published?: CVE-2026-4873 was published on 2026-05-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

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