CVE-2026-55431

MEDIUMNVD 6.16.1
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.3% (26th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Trending — 3 sources updated this week

Also known asEUVD-2026-42140 (ENISA EUVD) · GHSA-v54h-cp2w-9x4g (GitHub Security Advisories)Source: ENISA EUVD

6.1EG
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: 0.3%CVSS: 6.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, coder open app opens external workspace-app URLs without validating the scheme or host. When an external app URL contains the $SESSION_TOKEN placeholder the CLI replaces it with the user's real session token before handing the URL to the OS open handler. Practical exploitation requires the victim to run coder open app against a workspace whose external app definition the attacker controls. Only a malicious template author can control external app URLs. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 applies a URL-scheme allowlist in the CLI and limits $SESSION_TOKEN substitution to trusted destinations like the web frontend. As a workaround, avoid running coder open app for untrusted workspaces.

CVSS v3
6.1
EG Score
6.1MEDIUMmedium confidence
EG Risk
28
EG Risk 28/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity61% × 45%
Impact severity (EG Severity): CVSS 6.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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
0.3%
EPSS %ILE
26th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.1): severity, escalated by confirmed exploitation. This CVE's 6.1 is its impact severity (EG Severity), not escalated.

EG Severity
6.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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)14 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 total (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

July 6, 2026

Last Modified

July 8, 2026

Advisory Details (6)

Auto-updated Jul 8, 2026
Patch available. Sources: github_pr, github_release, github.
GitHub advisoryMentions a patch (unverified)

Session token leaked to arbitrary hosts via `coder open app` for external workspace apps · Advisory · coder/coder · GitHub

https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g
GitHub release Patch Available

v2.34.2 [SECURITY]

Patch available: coder/coder v2.34.2

https://github.com/coder/coder/releases/tag/v2.34.2
GitHub release Patch Available

v2.33.8 [SECURITY]

Patch available: coder/coder v2.33.8

https://github.com/coder/coder/releases/tag/v2.33.8
GitHub release Patch Available

v2.32.7 [SECURITY]

Patch available: coder/coder v2.32.7

https://github.com/coder/coder/releases/tag/v2.32.7
GitHub release Patch Available

v2.29.17 [SECURITY]

Patch available: coder/coder v2.29.17

https://github.com/coder/coder/releases/tag/v2.29.17
GitHub pull request

fix: prevent session token exfiltration via external app URLs

Fix merged in coder/coder PR #26146 on 2026-06-11 — awaiting tagged release

https://github.com/coder/coder/pull/26146

Vendor Advisories for CVE-2026-55431(1)

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

Affected Packages

(2 across 1 ecosystem)
Go(2)
PackageVulnerable rangeFix by version rangeDependents
github.com/coder/coder—
  • every version on: no fix on record
—
github.com/coder/coder/v2—
  • 2.34.0 up to 2.34.2: fixed in 2.34.2
  • 2.33.0 up to 2.33.8: fixed in 2.33.8
  • 2.30.0 up to 2.32.7: fixed in 2.32.7
  • every version up to 2.29.17: fixed in 2.29.17
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 39× 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 156 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 56 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  3. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  4. 2026-10-25 14:18 UTCEG score recompute
  5. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  6. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  7. 2026-10-22 21:16 UTCEG score recompute
  8. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  9. 2026-10-21 20:55 UTCOSV refresh
  10. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  11. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  12. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  14. 2026-10-18 03:30 UTCEG score recompute
  15. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  16. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  17. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  18. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  19. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  20. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  21. 2026-10-12 15:55 UTCEG score recompute
  22. 2026-10-11 19:39 UTCEG score recompute
  23. 2026-10-11 16:54 UTCEG score recompute
  24. 2026-10-11 14:17 UTCEG score recompute
  25. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.3% · 25th percentile
Show 75 more
  1. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  3. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  4. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  5. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  6. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  7. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  8. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  9. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  10. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  11. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  12. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  13. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  14. 2026-09-28 13:41 UTCEG score recompute
  15. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  16. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  17. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  18. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  19. 2026-09-23 06:22 UTCEG score recompute
  20. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  21. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  22. 2026-09-18 05:57 UTCEG score recompute
  23. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  24. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  25. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  26. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  27. 2026-09-14 07:49 UTCEG score recompute
  28. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  29. 2026-09-13 08:42 UTCEG score recompute
  30. 2026-09-12 03:50 UTCEG score recompute
  31. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  32. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  33. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  34. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  35. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  36. 2026-09-05 22:59 UTCEG score recompute
  37. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  38. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  39. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  40. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  41. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  42. 2026-08-30 07:59 UTCEG score recompute
  43. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  44. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  45. 2026-08-27 21:57 UTCEG score recompute
  46. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  47. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  48. 2026-08-26 13:54 UTCEG score recompute
  49. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 26th percentile
  50. 2026-08-24 22:12 UTCEG score recompute
  51. 2026-08-23 23:06 UTCEG score recompute
  52. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  53. 2026-08-22 00:38 UTCEG score recompute
  54. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  55. 2026-08-21 01:31 UTCEG score recompute
  56. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  57. 2026-08-20 02:25 UTCEG score recompute
  58. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  59. 2026-08-18 22:29 UTCEG score recompute
  60. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  61. 2026-08-17 22:39 UTCEG score recompute
  62. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  63. 2026-08-16 21:02 UTCEG score recompute
  64. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  65. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  66. 2026-08-15 21:56 UTCEG score recompute
  67. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  68. 2026-08-13 23:43 UTCEG score recompute
  69. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  70. 2026-08-13 00:37 UTCEG score recompute
  71. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  72. 2026-08-12 01:30 UTCEG score recompute
  73. 2026-08-11 02:24 UTCEG score recompute
  74. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  75. 2026-08-10 03:18 UTCEG score recompute

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-55431?
CVE-2026-55431 is a medium-severity vulnerability; its CVE record was published on July 6, 2026. Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, coder open app opens external workspace-app URLs without validating the scheme or host. When an external app URL contains the $SESSIONTOKEN placeholder the…
When was the CVE record for CVE-2026-55431 published?
The CVE record for CVE-2026-55431 was published on July 6, 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 July 8, 2026; the record at its source may have been updated since.
Is CVE-2026-55431 actively exploited?
CVE-2026-55431 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55431?
CVE-2026-55431 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2026-55431?
A fix for CVE-2026-55431 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55431 are linked in the Vendor Advisories panel on this page.

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