CVE-2026-4873

MEDIUMNVD 5.95.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

Score 5.9 from GitHub Security Advisory published 2026-05-13. NVD baseline CVSS 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
5.9EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 5.9Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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 v3
5.9
EG Score
5.9MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity59% × 45%
The EG Score, 5.9 of 10.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.4%
EPSS %ILE
27th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

May 13, 2026

Last Modified

September 15, 2026

Advisory Details (4)

Auto-updated May 14, 2026
Patch available.
Web page

oss-security - [ADVISORY] curl: CVE-2026-4873: connection reuse ignores TLS requirement

http://www.openwall.com/lists/oss-security/2026/04/29/7
Web page

HackerOne

https://hackerone.com/reports/3621851
Web page
https://curl.se/docs/CVE-2026-4873.json
Web page

curl - connection reuse ignores TLS requirement - CVE-2026-4873

https://curl.se/docs/CVE-2026-4873.html

Vendor Advisories for CVE-2026-4873(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibcurl4t64 (8.18.0-1ubuntu2.1) @ resolute2026-09-15ubuntu
redhatcurl-main-8.20.0-0.1.hum12026-05-02redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(6 across 6 ecosystems)
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 8.20.0-r0: fixed in 8.20.0-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
curl—
  • 7.20.0 up to 8.20.0-r0: fixed in 8.20.0-r0
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.74.0-1.3 ... 8.9.1-2~bpo12+1 (219 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
curl7.88.1-10 ... 8.9.1-2~bpo12+1 (184 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
curl8.14.1-2, 8.14.1-2+deb13u1, 8.14.1-2+deb13u2, 8.14.1-2+deb13u2~bpo13+1, 8.14.1-2+deb13u3
  • every version up to 8.14.1-2+deb13u4: fixed in 8.14.1-2+deb13u4
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
curl8.14.1-2 ... 8.20.0~rc1-1+exp3 (45 versions)
  • every version up to 8.20.0~rc2-1: fixed in 8.20.0~rc2-1
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 32× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 251 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 151 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  2. 2026-10-12 16:00 UTCEG score recompute
  3. 2026-10-11 19:43 UTCEG score recompute
  4. 2026-10-11 16:58 UTCEG score recompute
  5. 2026-10-11 14:22 UTCEG score recompute
  6. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  7. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  8. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  9. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  10. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  11. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  12. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  13. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  14. 2026-10-04 22:48 UTCOSV refresh
  15. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  16. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  17. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  18. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  19. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  20. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 27th percentile
  21. 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  22. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  23. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  24. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  25. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 25th percentile
Show 75 more
  1. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-09-15 07:26 UTCVendor advisory
  3. 2026-09-15 07:26 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  4. 2026-09-15 06:40 UTCEG score recompute
  5. 2026-09-15 06:40 UTCVendor advisory
  6. 2026-09-15 06:40 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  7. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  8. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  9. 2026-09-11 09:53 UTCOSV refresh
  10. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  11. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  12. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  14. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  15. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  17. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  18. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  20. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  21. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  22. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  23. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  24. 2026-08-23 17:58 UTCEG score recompute
  25. 2026-08-23 17:58 UTCVendor advisory
  26. 2026-08-23 17:58 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  27. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  28. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  29. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  30. 2026-08-20 21:33 UTCEG score recompute
  31. 2026-08-20 21:33 UTCVendor advisory
  32. 2026-08-20 21:33 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  33. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  34. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  35. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  36. 2026-08-17 10:44 UTCEG score recompute
  37. 2026-08-17 10:44 UTCVendor advisory
  38. 2026-08-17 10:44 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  39. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  40. 2026-08-16 04:08 UTCEG score recompute
  41. 2026-08-16 04:08 UTCVendor advisory
  42. 2026-08-16 04:08 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  43. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  44. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  45. 2026-08-14 02:36 UTCEG score recompute
  46. 2026-08-14 02:36 UTCVendor advisory
  47. 2026-08-14 02:36 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  48. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  49. 2026-08-12 15:54 UTCEG score recompute
  50. 2026-08-12 15:54 UTCVendor advisory
  51. 2026-08-12 15:54 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  52. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  53. 2026-08-11 07:17 UTCEG score recompute
  54. 2026-08-11 07:17 UTCVendor advisory
  55. 2026-08-11 07:17 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  56. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  57. 2026-08-10 05:49 UTCEG score recompute
  58. 2026-08-10 05:49 UTCVendor advisory
  59. 2026-08-10 05:49 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  60. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  61. 2026-08-09 04:21 UTCEG score recompute
  62. 2026-08-09 04:21 UTCVendor advisory
  63. 2026-08-09 04:21 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  64. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  65. 2026-08-08 02:53 UTCEG score recompute
  66. 2026-08-08 02:53 UTCVendor advisory
  67. 2026-08-08 02:53 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  68. 2026-08-07 01:25 UTCEG score recompute
  69. 2026-08-07 01:25 UTCVendor advisory
  70. 2026-08-07 01:25 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  71. 2026-08-06 13:47 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  72. 2026-08-05 21:43 UTCEG score recompute
  73. 2026-08-05 21:43 UTCVendor advisory
  74. 2026-08-05 21:43 UTCGHSA enrichmentGHSA-5fgw-rv54-prjx · GitHub CVSS 5.9
  75. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.3% · 25th percentile

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Frequently asked(5)

What is CVE-2026-4873?
CVE-2026-4873 is a medium-severity vulnerability; its CVE record was published on May 13, 2026. 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…
When was the CVE record for CVE-2026-4873 published?
The CVE record for CVE-2026-4873 was published on May 13, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 15, 2026; the record at its source may have been updated since.
Is CVE-2026-4873 actively exploited?
CVE-2026-4873 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (27th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-4873?
CVE-2026-4873 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-4873?
A fix for CVE-2026-4873 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-4873 are linked in the Vendor Advisories panel on this page.

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