CVE-2026-27840

MEDIUMPre-NVD 4.34.3
EchelonGraph scoreMEDIUM confidence

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

Score 4.3 from GitHub Security Advisory (severity: MODERATE) published 2026-02-27. A secondary CVSS source baseline 4.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week

Also known asEUVD-2026-8789 (ENISA EUVD) · GHSA-6mq3-xmgp-pjm5 (GitHub Security Advisories) · GO-2026-4573 (OSV.dev)Source: ENISA EUVD

4.3EG
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: 0.2%CVSS: 4.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

ZITADEL is an open source identity management platform. Starting in version 2.31.0 and prior to versions 3.4.7 and 4.11.0, opaque OIDC access tokens in the v2 format truncated to 80 characters are still considered valid. Zitadel uses a symmetric AES encryption for opaque tokens. The cleartext payload is a concatenation of a couple of identifiers, such as a token ID and user ID. Internally Zitadel has 2 different versions of token payloads. v1 tokens are no longer created, but are still verified as to not invalidate existing session after upgrade. The cleartext payload has a format of :. v2 tokens distinguished further where the token_id is of the format v2_-at_. V1 token authZ/N session data is retrieved from the database using the (simple) token_id value and user_id value. The user_id (called subject in some parts of our code) was used as being the trusted user ID. V2 token authZ/N session data is retrieved from the database using the oidc_session_id and access_token_id and in this case the user_id from the token is ignored and taken from the session data in the database. By truncating the token to 80 chars, the user_id is now missing from the cleartext of the v2 token. The back-end still accepts this for above reasons. This issue is not considered exploitable, but may look awkward when reproduced. The patch in versions 4.11.0 and 3.4.7 resolves the issue by verifying the user_id from the token against the session data from the database. No known workarounds are available.

CVSS v3
4.3
EG Score
4.3MEDIUMmedium confidence
EG Risk
19
EG Risk 19/100

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)
Severity43% × 45%
Impact severity (EG Severity): CVSS 4.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 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
0.2%
EPSS %ILE
5th
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 (4.3): severity, escalated by confirmed exploitation. This CVE's 4.3 is its impact severity (EG Severity), not escalated.

EG Severity
4.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

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.

The score's inputs: 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

February 26, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 4, 2026
Patch available. Sources: github, github_release.
GitHub advisoryMentions a patch (unverified)

Truncated opaque tokens are still valid · Advisory · zitadel/zitadel · GitHub

https://github.com/zitadel/zitadel/security/advisories/GHSA-6mq3-xmgp-pjm5
GitHub release Patch Available

v4.11.0

Patch available: zitadel/zitadel v4.11.0

https://github.com/zitadel/zitadel/releases/tag/v4.11.0
GitHub release Patch Available

v3.4.7

Patch available: zitadel/zitadel v3.4.7

https://github.com/zitadel/zitadel/releases/tag/v3.4.7

Patch Availability(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
gogithub.com/zitadel/zitadel @ 4.11.0 (fixes >= 4.0.0, < 4.11.0)—ghsa
gogithub.com/zitadel/zitadel @ 3.4.7 (fixes >= 3.0.0, < 3.4.7)—ghsa
gogithub.com/zitadel/zitadel—ghsa
gogithub.com/zitadel/zitadel @ 1.80.0-v2.20.0.20260216092519-feab8e1fa371 (fixes < 1.80.0-v2.20.0.20260216092519-feab8e1fa371)—ghsa

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

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFix by version rangeDependents
github.com/zitadel/zitadel—
  • 4.0.0 up to 4.11.0: fixed in 4.11.0
  • 3.0.0 up to 3.4.7: fixed in 3.4.7
  • 2.31.0 through 2.71.19: no fix on record
  • every version up to 1.80.0-v2.20.0.20260216092519-feab8e1fa371: fixed in 1.80.0-v2.20.0.20260216092519-feab8e1fa371
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× 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 96 of 101 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. 4 repeat rows among the latest 100 are merged into the row they repeat. The 5 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  2. 2026-11-01 07:56 UTCGHSA enrichmentGHSA-6mq3-xmgp-pjm5 · GitHub severity MODERATE · GitHub CVSS 4.3
  3. 2026-11-01 07:56 UTCEG score recompute
  4. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  5. 2026-10-31 00:25 UTCOSV refresh
  6. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  7. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  8. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  9. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  10. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  11. 2026-10-25 14:38 UTCEG score recompute
  12. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 15th percentile
  13. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-23 04:11 UTCEG score recompute
  15. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  20. 2026-10-18 03:51 UTCEG score recompute
  21. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  22. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  23. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  24. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  25. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 12th percentile
Show 71 more
  1. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  2. 2026-10-12 16:17 UTCEG score recompute
  3. 2026-10-11 19:59 UTCEG score recompute
  4. 2026-10-11 17:12 UTCEG score recompute
  5. 2026-10-11 14:43 UTCEG score recompute
  6. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  7. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  8. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  9. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  10. 2026-10-08 13:35 UTCOSV refresh
  11. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  12. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  13. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  14. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  15. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  16. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  17. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  18. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  19. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  20. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.2% · 12th percentile
  21. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  22. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  23. 2026-09-18 19:20 UTCOSV refresh
  24. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  25. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  26. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  27. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  28. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  29. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  30. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  31. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  32. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  33. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  34. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  35. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  36. 2026-08-30 22:17 UTCOSV refresh
  37. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  38. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  39. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  40. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  41. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  42. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  43. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  44. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  45. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  46. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  47. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.1% · 4th percentile
  48. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  49. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  50. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  51. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  52. 2026-08-14 08:58 UTCEG score recompute
  53. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  54. 2026-08-13 00:57 UTCEG score recompute
  55. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  56. 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  57. 2026-08-11 06:52 UTCEG score recompute
  58. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  59. 2026-08-10 08:43 UTCEG score recompute
  60. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  61. 2026-08-09 08:35 UTCEG score recompute
  62. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  63. 2026-08-07 20:38 UTCEG score recompute
  64. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  65. 2026-08-06 02:59 UTCEG score recompute
  66. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  67. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  68. 2026-08-04 05:01 UTCEG score recompute
  69. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  70. 2026-08-02 19:30 UTCEG score recompute
  71. 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.1% · 3rd percentile

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Frequently asked(5)

What is CVE-2026-27840?
CVE-2026-27840 is a medium-severity vulnerability; its CVE record was published on February 26, 2026. ZITADEL is an open source identity management platform. Starting in version 2.31.0 and prior to versions 3.4.7 and 4.11.0, opaque OIDC access tokens in the v2 format truncated to 80 characters are still considered valid. Zitadel uses a symmetric AES encryption for opaque tokens. The cleartext…
When was the CVE record for CVE-2026-27840 published?
The CVE record for CVE-2026-27840 was published on February 26, 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 June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-27840 actively exploited?
CVE-2026-27840 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (5th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-27840?
CVE-2026-27840 has a CVSS base score of 4.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-27840?
A fix for CVE-2026-27840 is available: update to the fixed version the vendor names in its advisory.

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