CVE-2026-55200

HIGHNVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under NVD CVSS v3. EPSS exploit probability: 4.0%, top 10% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Trending — 4 sources updated this weekElevated
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS: 8.3Exploit: Elevated riskExposed: 0

A fix is available — apply it.

libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.

CVSS v3
8.3
EG Score
8.3(medium)
EG Risk
53(Track*)
EG Risk 53/100SSVC: 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
Severity83% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
4%
EPSS %ILE
90%
KEV
Not listed

Published

June 17, 2026

Last Modified

July 14, 2026

Advisory Details (5)

Auto-updated Jun 30, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://web.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc
generic

libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c | Advisories | VulnCheck

https://www.vulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-c
github_pr

transport.c: Additional boundary checks for packet length

Fix merged in libssh2/libssh2 PR #2052 on 2026-06-12 — awaiting tagged release

https://github.com/libssh2/libssh2/pull/2052
github_commit

commit 97acf3dfda80 (libssh2/libssh2)

Fix landed in libssh2/libssh2 commit 97acf3dfda80 — awaiting tagged release

https://github.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8
generic

exploitarium/libssh2-cve-2026-55200-poc at main · bikini/exploitarium · GitHub

https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc

Vendor Advisories for CVE-2026-55200(3)

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 / EcosystemFixed in / PatchReleasedSource
ubuntulibssh2-1t64 (1.11.0-4.1ubuntu0.24.04.2) @ noble2026-08-24ubuntu
redhatlibssh2-main-1.11.1-8.hum12026-06-25redhat

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

(7 across 6 ecosystems)
Alpine:v3.24(2)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r3—
rust—1.96.1-r0—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r2—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r2—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
libssh2—1.11.1-r3—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-11.11.1-1+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libssh21.11.1-1, 1.11.1-2, 1.11.1-31.11.1-4—

Weakness Classification(1)

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 25× in last 7d / 154× 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 330 total refreshes for this CVE.

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

Publicly available exploits

(2 references)

Working exploit code is in the public domain (2 GitHub PoCs). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCxd20111/CVE-2026-55200
    First seen Jun 29, 2026

    CVE-2026-55200 - Critical libssh2 Remote Code Execution Vulnerability

    Open source ↗
  • GitHub PoC0xBlackash/CVE-2026-55200
    First seen Jun 23, 2026

    CVE-2026-55200

    Open source ↗

Frequently asked(5)

What is CVE-2026-55200?
CVE-2026-55200 is a high vulnerability published on June 17, 2026. libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2transportread() that fails to enforce upper bounds on packetlength field. Remote attackers can send crafted SSH packets with excessively large packetlength values to corrupt heap memory and achieve…
When was CVE-2026-55200 disclosed?
CVE-2026-55200 was first published in the National Vulnerability Database on June 17, 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-2026-55200 actively exploited?
CVE-2026-55200 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4% probability of exploitation in the next 30 days, which ranks it in the top 10.2% of all scored CVEs.
What is the CVSS score of CVE-2026-55200?
CVE-2026-55200 has a CVSS v3 base score of 8.3 (NVD).
How do I remediate CVE-2026-55200?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55200, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55200

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