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CVE Record

CVE-2026-62317: Logto: ReDoS via unescaped user input in email subaddressing regex (blockSubaddressing)

Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.41.0, Logto's email subaddressing blocklist in packages/core/src/libraries/sign-in-experience/email-blocklist-policy.ts used the attacker-controlled domain from email input to construct subaddressingRegex when blockSubaddressing was enabled. The permissive emailRegEx accepted multiple at signs and regular expression metacharacters, and POST /api/experience/verification/verification-code could therefore cause catastrophic backtracking in subaddressingRegex.test(email). The resulting event-loop stall could make authentication, token issuance, SSO, and the administrative console unavailable. This issue is fixed in version 1.41.0.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Logto versions before 1.41.0 can be remotely forced into excessive processing when email subaddress blocking is enabled. A crafted verification-code request may stall the application, disrupting authentication, token issuance, SSO, and administration. The issue affects availability, not disclosed confidentiality or integrity.

Executive priority

Prioritize remediation for externally reachable production identity systems. Authentication outages can interrupt customer access and internal administration even though no data theft or modification is described. Upgrade promptly and verify every production and recovery instance.

Technical view

Attacker-controlled email-domain text was inserted unescaped into a regular expression used by blockSubaddressing. Permissive email validation allowed metacharacters and multiple at signs, enabling catastrophic regex backtracking during verification-code processing. The CVSS 3.1 score is 7.5: network-accessible, low complexity, unauthenticated, and high availability impact.

Likely exposure

Deployments running Logto earlier than 1.41.0 are exposed when blockSubaddressing is enabled and the verification-code API is reachable. Internet-facing identity services have the greatest operational risk because one stalled event loop may affect several critical authentication functions.

Exploitation context

The supplied record does not identify CISA KEV listing or evidence of active exploitation. The CVSS assessment indicates remote, low-complexity exploitation requiring neither privileges nor user interaction. Treat exposure as credible, but do not describe the vulnerability as actively exploited without additional evidence.

Researcher notes

The vulnerable path is packages/core/src/libraries/sign-in-experience/email-blocklist-policy.ts and is reached through POST /api/experience/verification/verification-code when blockSubaddressing is enabled. Root cause is unescaped user input in a dynamically constructed regex, classified as CWE-1333. The referenced pull request and commit document the correction.

Mitigation direction

  • Upgrade every Logto instance to version 1.41.0 or later.
  • Confirm the upgrade covers all replicas, workers, and disaster-recovery environments.
  • Review the vendor advisory for any additional deployment-specific guidance.
  • Monitor verification-code traffic and service latency until remediation is complete.

Validation and detection

  • Inventory deployed Logto versions and identify every instance below 1.41.0.
  • Determine whether blockSubaddressing is enabled in each vulnerable deployment.
  • Confirm the verification-code endpoint's external reachability and protective controls.
  • After upgrading, verify authentication, token issuance, SSO, and administrative-console availability.
  • Review telemetry for repeated verification-code requests correlated with event-loop stalls or latency spikes.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-1333: Exact CWE lookup

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description · low confidence lookup

Credential and access behavior lookup

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cve · low confidence lookup

CVE-2026-62317 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
5Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GitHub_M

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-62317Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
logto-iologto< 1.41.0Listed
Weakness

CWE details

CWE-1333

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-1333 · source CWE mapping

Inefficient Regular Expression Complexity

Inefficient Regular Expression Complexity represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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