CVE-2026-81036

HIGHPre-NVD 8.18.1—
EchelonGraph scoreHIGH confidence

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, ghsa, secondary
Trending — 4 sources updated this weekElevated
8.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.1Exploit: Elevated riskExposed: 0

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

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
8.1(high)
EG Risk
52(Track*)
EG Risk 52/100SSVC: 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
Severity81% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

August 26, 2026

Last Modified

August 29, 2026

Advisory Details (4)

Auto-updated Aug 26, 2026
No patch confirmed yet.
generic

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
generic

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
generic

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
generic

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 21× in last 7d / 21× 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.

  1. 2026-08-30 02:34 UTCEG score recompute
  2. 2026-08-30 02:34 UTCGHSA enrichment
  3. 2026-08-30 01:22 UTCEPSS rescore
  4. 2026-08-29 14:59 UTCGHSA enrichment
  5. 2026-08-29 03:23 UTCEG score recompute
  6. 2026-08-29 03:23 UTCGHSA enrichment
  7. 2026-08-29 02:48 UTCEG score recompute
  8. 2026-08-29 02:48 UTCGHSA enrichment
  9. 2026-08-29 02:39 UTCEG score recompute
  10. 2026-08-29 02:39 UTCGHSA enrichment
  11. 2026-08-28 21:42 UTCEPSS rescore
  12. 2026-08-28 15:03 UTCGHSA enrichment
  13. 2026-08-28 03:25 UTCGHSA enrichment
  14. 2026-08-27 15:50 UTCEG score recompute
  15. 2026-08-27 15:50 UTCGHSA enrichment
  16. 2026-08-27 14:25 UTCEPSS rescore
  17. 2026-08-27 04:13 UTCEG score recompute
  18. 2026-08-27 04:13 UTCGHSA enrichment
  19. 2026-08-26 16:37 UTCEG score recompute
  20. 2026-08-26 15:55 UTCEG score recompute
  21. 2026-08-26 15:54 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-81036?
CVE-2026-81036 is a high vulnerability 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 disclosed?
CVE-2026-81036 was first published in the National Vulnerability Database on August 26, 2026, with the most recent update on August 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-81036 actively exploited?
CVE-2026-81036 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 77.0% of all scored CVEs.
What is the CVSS score of CVE-2026-81036?
CVE-2026-81036 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-81036?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-81036, 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

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