CVE-2026-81036

HIGHPre-NVD 8.18.1
EchelonGraph scoreMEDIUM confidence

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

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-08-26. A secondary CVSS source baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this weekElevated
8.1EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.1Exploit: No code on recordExposed services: Not assessed

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

The CVE record's CNA (VulnCheck) lists stalwartlabs stalwart versions up to and including 0.16.19 as affected. No release containing a fix is confirmed on record.

Stalwart Mail Server does not compare an OAuth redirect target against any registered destination in its default configuration. The validation routine in crates/http/src/auth/oauth/registration.rs returns success immediately when the client-authentication requirement is disabled, and that requirement is false in the shipped settings, so the supplied redirect value is neither matched against a registered client nor otherwise constrained. The value is stored with the authorization code, and the login page reads it back and sends the browser to it with the code attached. A request naming a destination the attacker controls therefore delivers a valid authorization code there once the account holder authenticates, and because the token endpoint checks only that the redirect presented at exchange matches the one recorded with the code, the same party can exchange it for access and refresh tokens and read the account's mail.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
52
EG Risk 52/100

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 (value × EchelonGraph’s weight)
Severity81% × 45%
The EG Score, 8.1 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.
Exploitation public PoC (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: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.4%
EPSS %ILE
31st
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low, Track* at medium and Attend at high mission impact.

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation public PoC (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

August 26, 2026

Last Modified

September 24, 2026

Advisory Details (4)

Auto-updated Aug 26, 2026
No fix on record yet.
Web page

Stalwart Mail Server through 0.16.19 Authorization Code Disclosure via Unvalidated OAuth redirect_uri | Advisories | VulnCheck

https://www.vulncheck.com/advisories/stalwart-mail-server-through-0.16.19-authorization-code-disclosure-via-unvalidated-oauth-redirect-uri
Web page

stalwart/crates/http/src/auth/oauth/registration.rs at v0.16.19 · stalwartlabs/stalwart · GitHub

https://github.com/stalwartlabs/stalwart/blob/v0.16.19/crates/http/src/auth/oauth/registration.rs
Web page

OAuth Authorization Code Token Theft via Unvalidated redirect_uri - https://github.com/stalwartlabs/stalwart/security/advisories/GHSA-6xx8-3vx5-5rv3 · Issue #3205 · stalwartlabs/stalwart · GitHub

https://github.com/stalwartlabs/stalwart/issues/3205
Web page

GitHub - stalwartlabs/stalwart: All-in-one Mail & Collaboration server. Secure, scalable and fluent in every protocol (IMAP, JMAP, SMTP, CalDAV, CardDAV, WebDAV). · GitHub

https://github.com/stalwartlabs/stalwart

Vendor Advisories for CVE-2026-81036(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 104× 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 183 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 83 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  2. 2026-10-13 06:23 UTCEG score recompute
  3. 2026-10-13 06:23 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  4. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  5. 2026-10-12 14:57 UTCEG score recompute
  6. 2026-10-11 19:21 UTCEG score recompute
  7. 2026-10-11 16:37 UTCEG score recompute
  8. 2026-10-11 13:55 UTCEG score recompute
  9. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 31st percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  11. 2026-10-10 06:05 UTCEG score recompute
  12. 2026-10-10 06:05 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  14. 2026-10-09 03:22 UTCEG score recompute
  15. 2026-10-09 03:22 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  16. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  17. 2026-10-08 01:49 UTCEG score recompute
  18. 2026-10-08 01:48 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  19. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  20. 2026-10-07 06:52 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  21. 2026-10-06 19:16 UTCEG score recompute
  22. 2026-10-06 19:16 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  23. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  24. 2026-10-06 07:35 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  25. 2026-10-05 18:55 UTCEG score recompute
Show 75 more
  1. 2026-10-05 18:55 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  2. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  3. 2026-10-05 07:17 UTCEG score recompute
  4. 2026-10-05 07:17 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  5. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  6. 2026-10-04 19:41 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  7. 2026-10-04 06:57 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  8. 2026-10-03 19:22 UTCEG score recompute
  9. 2026-10-03 19:22 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  10. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  11. 2026-10-03 06:43 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  12. 2026-10-02 19:06 UTCEG score recompute
  13. 2026-10-02 19:06 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  14. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  15. 2026-10-02 07:30 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  16. 2026-10-01 19:55 UTCEG score recompute
  17. 2026-10-01 19:55 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  19. 2026-10-01 07:33 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  20. 2026-09-30 19:58 UTCEG score recompute
  21. 2026-09-30 19:58 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  22. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  23. 2026-09-30 06:02 UTCEG score recompute
  24. 2026-09-30 06:02 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  25. 2026-09-29 08:55 UTCEG score recompute
  26. 2026-09-29 08:55 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  27. 2026-09-28 21:20 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  28. 2026-09-28 07:27 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  29. 2026-09-27 19:52 UTCEG score recompute
  30. 2026-09-27 19:52 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  31. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  32. 2026-09-27 08:16 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  33. 2026-09-26 20:33 UTCEG score recompute
  34. 2026-09-26 20:33 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  35. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 30th percentile
  36. 2026-09-25 08:49 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  37. 2026-09-24 21:14 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  38. 2026-09-24 17:07 UTCEG score recompute
  39. 2026-09-24 17:07 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  40. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 43rd percentile
  41. 2026-09-24 05:31 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  42. 2026-09-23 17:55 UTCEG score recompute
  43. 2026-09-23 17:55 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  44. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  45. 2026-09-23 06:20 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  46. 2026-09-22 18:45 UTCEG score recompute
  47. 2026-09-22 18:44 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  48. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  49. 2026-09-22 06:54 UTCEG score recompute
  50. 2026-09-22 06:54 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  51. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  52. 2026-09-21 19:19 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  53. 2026-09-21 07:43 UTCEG score recompute
  54. 2026-09-21 07:43 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  55. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  56. 2026-09-20 20:07 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  57. 2026-09-20 08:31 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  58. 2026-09-19 20:42 UTCEG score recompute
  59. 2026-09-19 20:42 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  60. 2026-09-19 09:06 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  61. 2026-09-18 21:31 UTCEG score recompute
  62. 2026-09-18 21:31 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  63. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  64. 2026-09-18 08:34 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  65. 2026-09-17 20:57 UTCEG score recompute
  66. 2026-09-17 20:57 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  67. 2026-09-17 09:07 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  68. 2026-09-16 21:31 UTCEG score recompute
  69. 2026-09-16 21:31 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  70. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  71. 2026-09-16 09:18 UTCEG score recompute
  72. 2026-09-16 09:18 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  73. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  74. 2026-09-15 20:59 UTCGHSA enrichmentGHSA-g6qf-h8rr-h574 · GitHub severity HIGH · GitHub CVSS 8.1
  75. 2026-09-15 08:50 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-81036?
CVE-2026-81036 is a high-severity vulnerability; its CVE record was published on August 26, 2026. Stalwart Mail Server does not compare an OAuth redirect target against any registered destination in its default configuration. The validation routine in crates/http/src/auth/oauth/registration.rs returns success immediately when the client-authentication requirement is disabled, and that…
When was CVE-2026-81036 made public?
CVE-2026-81036 was made public on August 26, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 26, 2026. EchelonGraph's copy of the record carries a last-modified date of September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-81036 actively exploited?
CVE-2026-81036 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (31st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-81036?
CVE-2026-81036 has a CVSS base score of 8.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-81036?
No fix for CVE-2026-81036 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's CNA (VulnCheck) lists stalwartlabs stalwart versions up to and including 0.16.19 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-81036 are linked in the Vendor Advisories panel on this page.

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