CVE-2026-56123

HIGHPre-NVD 8.18.1—
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-06-25. the CNA's CVSS baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, epss, ghsa
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.1Exploit: None knownExposed: 0

A fix is available — apply it.

socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read through a signed char field causing a negative bytes_to_read value that is implicitly converted to size_t, resulting in an unbounded heap write into the 262-byte reply buffer with attacker-controlled size and content.

CVSS v3
8.1
EG Score
8.1(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

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
Severity81% × 45%
Exploitation1% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
44%
KEV
Not listed

Published

June 25, 2026

Last Modified

July 14, 2026

Advisory Details (2)

Auto-updated Jul 12, 2026
Patch available.
generic

socat 1.8.0.0 - 1.8.1.1 Heap Buffer Overflow via SOCKS5 Reply Parser | Advisories | VulnCheck

https://www.vulncheck.com/advisories/socat-heap-buffer-overflow-via-socks5-reply-parser
generic Patch Available
http://www.dest-unreach.org/socat/CHANGES

Vendor Advisories for CVE-2026-56123(2)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntusocat (1.8.1.1-1ubuntu0.1) @ resolute2026-08-30ubuntu

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:v3.21(1)
PackageVulnerable rangeFixed inDependents
socat—1.8.1.2-r0—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
socat—1.8.1.2-r0—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
socat—1.8.1.2-r0—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
socat—1.8.1.2-r0—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
socat1.8.0.3-1 ... 2.0.0~beta9-1 (12 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
socat1.8.0.3-1, 1.8.1.0-1, 1.8.1.0-2, 1.8.1.1-1, 1.8.1.1-21.8.1.3-1—

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 5× in last 7d / 87× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 284 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-56123?
CVE-2026-56123 is a high vulnerability published on June 25, 2026. socat versions 1.8.0.0 through 1.8.1.1 contain a heap-based buffer overflow vulnerability that allows a malicious SOCKS5 proxy server to overwrite adjacent heap memory by exploiting a sign-extension flaw in the DOMAINNAME reply parser. During connection setup, the domain name length byte is read…
When was CVE-2026-56123 disclosed?
CVE-2026-56123 was first published in the National Vulnerability Database on June 25, 2026, with the most recent update on July 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56123 actively exploited?
CVE-2026-56123 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 55.8% of all scored CVEs.
What is the CVSS score of CVE-2026-56123?
CVE-2026-56123 has a CVSS v4.0 base score of 8.1 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-56123?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56123, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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