5.9

CVE-2026-4873: curl

CVSS: 5.9v3.1MediumModified
AliasesALPINE-CVE-2026-4873UBUNTU-CVE-2026-4873DEBIAN-CVE-2026-4873
Published 13-05-2026Last modified 15-09-2026
Open JSON

Vulnerability summary

CVE-2026-4873 is a medium (CVSS 5.9) vulnerability in curl. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.3% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
34/100
0100
Medium · default modelHow is this calculated?
CVSS score
5.9/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · +0.03 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Advisory lineage

Upstream 0 · Downstream 7 · Related 7
OPENSUSE-SU-2026:10674-1OPENSUSE-SU-2026:20973-1RHSA-2026:12916SUSE-SU-2026:22146-1SUSE-SU-2026:22156-1SUSE-SU-2026:2703-1

Timeline

  1. 13-05-2026
    PublishedVulnerability first disclosed.
  2. 15-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

+0.03 pp

From 0.33% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.36%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (hackerone.com)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Alpine1 product
  • curl≥ 7.20.0, < 8.14.1-r3 | ≥ 7.20.0, < 8.14.1-r4 | ≥ 7.20.0, < 8.20.0-r0
Chainguard1 product
  • libcurl4All versions (No fix recorded)
Curl1 product
  • curl≥ 7.20.0, < 8.14.2 | ≥ 8.15.0, < 8.16.1 | ≥ 8.17.0, < 8.20.0 | ≥ ec3bb8f727405642a471b4b1b9eb0118fc003104, < 507e7be573b0a76fca597b75ff7cb27a66e7d865 | 8.19.0 | 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
Debian1 product
  • curlAll versions (No fix recorded) | < 8.14.1-2+deb13u4 | < 8.20.0~rc2-1
Haxx1 product
  • curl≥ 7.20.0, < 8.20.0
Ubuntu1 product
  • curlAll versions (No fix recorded) | < 7.81.0-1ubuntu1.24 | < 8.5.0-2ubuntu10.9 | < 8.14.1-2ubuntu1.3 | < 8.18.0-1ubuntu2.1
Wolfi1 product
  • libcurl4All versions (No fix recorded)

7 vendors · 7 products

References

10 links