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CVE Record

CVE-2021-23365: Authentication Bypass

The package github.com/tyktechnologies/tyk-identity-broker before 1.1.1 are vulnerable to Authentication Bypass via the Go XML parser which can cause SAML authentication bypass. This is because the XML parser doesn’t guarantee integrity in the XML round-trip (encoding/decoding XML data).

MediumCVSS 4.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-23365 affects Tyk Identity Broker before 1.1.1. A flaw in XML handling could let a SAML login be accepted incorrectly, creating an authentication bypass risk. The public sources rate this medium severity, with low confidentiality and integrity impact and high attack complexity.

Executive priority

Treat this as a moderate-priority identity control issue. It is not documented as actively exploited in the supplied sources, but affected SAML deployments should be upgraded promptly because authentication bypass can undermine access decisions.

Technical view

The issue is in github.com/TykTechnologies/tyk-identity-broker before 1.1.1. The Go XML parser used in SAML processing did not guarantee integrity across XML encode/decode round trips, which could permit SAML authentication bypass under specific conditions. Sources do not provide exploit details or broad affected deployment context.

Likely exposure

Exposure is likely limited to deployments running Tyk Identity Broker versions before 1.1.1 and using SAML authentication flows. Risk is higher where the broker protects administrative, API, or sensitive application access, especially if reachable over the network.

Exploitation context

The supplied data does not show CISA KEV listing or active exploitation. CVSS indicates network reachability, no privileges, no user interaction, high attack complexity, low confidentiality impact, low integrity impact, and no availability impact.

Researcher notes

Evidence points to XML round-trip integrity issues in SAML handling, fixed around release 1.1.1 through linked PR and commits. The source bundle lacks CWEs, exploitability conditions, and detection indicators, so validation should focus on version exposure and SAML deployment context.

Mitigation direction

  • Upgrade Tyk Identity Broker to version 1.1.1 or later.
  • Review the v1.1.1 release notes and linked fixes before rollout.
  • Prioritize deployments that use SAML for privileged or sensitive access.
  • If upgrade timing is unclear, check current Tyk vendor guidance.
  • Monitor authentication logs for unusual SAML login outcomes.

Validation and detection

  • Inventory all Tyk Identity Broker deployments and recorded versions.
  • Confirm no running deployment is below version 1.1.1.
  • Verify container images or binaries include the fixed release.
  • Confirm SAML authentication paths still work after upgrade.
  • Review access logs around SAML authentication for anomalies.
Prepared
Confidence
medium
Sources
7

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2021-23365 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.8 (3.1)
Known Exploited
No
Published

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

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
0Timeline events
0ADP providers
6Source 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
4.8CVSS 3.1MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N2.22.5Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

4.8Medium
CVSS 3.1 vector shape for CVE-2021-23365Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/agithub.com/TykTechnologies/tyk-identity-brokerunspecifiedListed
Weakness

CWE details

No CWE listed

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