CVE-2026-34956

MEDIUMNVD 5.95.9—
EchelonGraph scoreMEDIUM confidence

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

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
5.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A flaw was found in Open vSwitch. When Open vSwitch is configured with a conntrack flow using FTP helpers over the userspace datapath, a remote attacker can send a specially crafted FTP stream with an EPASV command exceeding 255 characters. This heap access error can lead to a crash, resulting in a Denial of Service (DoS) for the affected system.

CVSS v3
5.9
EG Score
5.9(medium)
EG Risk
27(Track)
EG Risk 27/100SSVC: 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
Severity59% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
34%
KEV
Not listed

Published

May 5, 2026

Last Modified

September 1, 2026

Advisory Details (3)

Auto-updated May 5, 2026
Patch available. Sources: redhat.
generic

oss-security - [ADVISORY] CVE-2026-34956: Open vSwitch: Invalid memory access in conntrack FTP alg.

http://www.openwall.com/lists/oss-security/2026/03/31/15
redhat

2453459 – (CVE-2026-34956) CVE-2026-34956 openvswitch: Open vSwitch: Denial of Service via malformed FTP EPASV command

https://bugzilla.redhat.com/show_bug.cgi?id=2453459
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-34956

Vendor Advisories for CVE-2026-34956(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
openvswitch2.15.0+ds1-10 ... 3.7.1-3 (62 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
openvswitch3.1.0-2 ... 3.7.1-3 (36 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
openvswitch3.5.0-1 ... 3.7.1-3 (14 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
openvswitch3.5.0-1 ... 3.7.0~git20260211.8c6ebf8-1~1.gbp9127d3 (11 versions)3.7.1-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 67× 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 215 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-34956?
CVE-2026-34956 is a medium vulnerability published on May 5, 2026. A flaw was found in Open vSwitch. When Open vSwitch is configured with a conntrack flow using FTP helpers over the userspace datapath, a remote attacker can send a specially crafted FTP stream with an EPASV command exceeding 255 characters. This heap access error can lead to a crash, resulting in a…
When was CVE-2026-34956 disclosed?
CVE-2026-34956 was first published in the National Vulnerability Database on May 5, 2026, with the most recent update on September 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-34956 actively exploited?
CVE-2026-34956 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 66.2% of all scored CVEs.
What is the CVSS score of CVE-2026-34956?
CVE-2026-34956 has a CVSS v3 base score of 5.9 (NVD).
How do I remediate CVE-2026-34956?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34956, 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.

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