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CVE Record

CVE-2021-32738: Utils.readChallengeTx does not verify the server account signature

js-stellar-sdk is a Javascript library for communicating with a Stellar Horizon server. The `Utils.readChallengeTx` function used in SEP-10 Stellar Web Authentication states in its function documentation that it reads and validates the challenge transaction including verifying that the `serverAccountID` has signed the transaction. In js-stellar-sdk before version 8.2.3, the function does not verify that the server has signed the transaction. Applications that also used `Utils.verifyChallengeTxThreshold` or `Utils.verifyChallengeTxSigners` to verify the signatures including the server signature on the challenge transaction are unaffected as those functions verify the server signed the transaction. Applications calling `Utils.readChallengeTx` should update to version 8.2.3, the first version with a patch for this vulnerability, to ensure that the challenge transaction is completely valid and signed by the server creating the challenge transaction.

MediumCVSS 6.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-32738 affects Stellar’s JavaScript SDK authentication helper. Some applications may have accepted a SEP-10 challenge transaction without confirming it was signed by the expected server account. This is an integrity risk for authentication flows, not a confidentiality or availability issue in the published scoring.

Executive priority

Treat as a moderate authentication integrity issue. Prioritize systems that use Stellar SEP-10 authentication and older js-stellar-sdk versions. The business urgency is highest where authentication decisions affect funds, account access, or transaction authority.

Technical view

In js-stellar-sdk before 8.2.3, Utils.readChallengeTx did not verify that serverAccountID signed the challenge transaction, despite documentation indicating it did. Applications using Utils.verifyChallengeTxThreshold or Utils.verifyChallengeTxSigners for signature verification are described as unaffected. The issue is CWE-287 with CVSS 3.1 score 6.5.

Likely exposure

Exposure is likely limited to applications using js-stellar-sdk below 8.2.3 for SEP-10 Stellar Web Authentication and relying on Utils.readChallengeTx alone for challenge validation. Applications that separately verified challenge signatures with the named SDK helpers are likely not exposed per the advisory description.

Exploitation context

The provided sources do not report active exploitation, and the CVE is not marked KEV. The CVSS vector indicates network reachability, low attack complexity, low privileges, no user interaction, and high integrity impact. No exploit details are provided in the source bundle.

Researcher notes

The core evidence is a mismatch between documented behavior and implementation: readChallengeTx claimed complete validation but omitted server signature verification before 8.2.3. Do not assume all SDK users are vulnerable; exposure depends on whether additional signature verification helpers were used.

Mitigation direction

  • Upgrade js-stellar-sdk to version 8.2.3 or later.
  • Review SEP-10 authentication code using Utils.readChallengeTx.
  • Ensure server account signatures are verified in the challenge validation path.
  • For uncertain implementations, follow Stellar’s advisory and release guidance.

Validation and detection

  • Inventory deployed applications using js-stellar-sdk.
  • Confirm package versions are 8.2.3 or later.
  • Search authentication code for direct Utils.readChallengeTx reliance.
  • Verify use of Utils.verifyChallengeTxThreshold or Utils.verifyChallengeTxSigners where applicable.
  • Add regression tests for rejected unsigned server challenge transactions.
Prepared
Confidence
high
Sources
4

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

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cwe · medium confidence lookup

CWE-287: Credential and account abuse lookup

Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2021-32738 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
6.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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
3Source 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
6.5CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N2.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

6.5Medium
CVSS 3.1 vector shape for CVE-2021-32738Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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
stellarjs-stellar-sdk< 8.2.3Listed
Weakness

CWE details

CWE-287

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

CWE-287 · source CWE mapping

Improper Authentication

Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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