Security readout for executives and security teams
Plain-English summary
Affected Mongoose clients may trust an impostor TLS server when using a multi-certificate CA bundle. An unauthenticated network attacker could intercept connections, expose credentials, alter traffic, or return malicious content. The defect affects versions before 7.23 and is fixed in 7.23.
Executive priority
Treat as an urgent remediation for confirmed affected clients, especially embedded systems handling credentials, updates, control traffic, or sensitive data. Rapidly determine whether the specific multi-certificate CA-bundle configuration is present, then upgrade and redeploy. Systems without that configuration should remain tracked until their non-exposure is documented.
Technical view
In Mongoose’s built-in TLS implementation, multi-certificate bundles are stored separately while the single-CA field remains empty. Certificate processing can then accept a Common Name match from the bundle without verifying the certificate signature. This breaks server authentication and permits a forged self-signed certificate to pass relevant checks.
Likely exposure
Exposure is limited to applications or embedded products using Mongoose before 7.23 as a TLS client with a multi-certificate CA bundle. Mongoose servers, clients using a single CA certificate, or deployments using another TLS implementation are not established as affected by the supplied evidence.
Exploitation context
The vulnerability is network-reachable, requires no privileges or user interaction, and has low stated attack complexity. The source bundle does not report known active exploitation and marks KEV false. Practical risk is highest where attackers can influence network traffic between an affected client and its intended server.
Researcher notes
The failure is CWE-295 improper certificate validation. The supplied description ties the bypass to mg_tls_init(), mg_tls_recv_cert(), tls_bundle_find(), and the omitted mg_tls_verify_cert_signature() call. Review downstream forks and vendored copies because application package versions may not reveal the embedded Mongoose revision.
Mitigation direction
- Upgrade Mongoose to version 7.23 or later.
- Rebuild and redeploy every application or firmware image containing the affected library.
- Prioritize clients carrying credentials, administrative traffic, updates, or safety-sensitive commands.
- Check the vendor advisory before relying on configuration changes as temporary mitigation.
Validation and detection
- Inventory applications and firmware containing Mongoose, including statically linked copies.
- Confirm the deployed Mongoose version from build records or production artifacts.
- Identify clients using built-in TLS with multi-certificate CA bundles.
- Verify rebuilt artifacts contain version 7.23 or later.
- Test that clients reject certificates lacking a valid chain to the configured trust store.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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.
CWE-295: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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.
Open ATT&CK lookupCredential 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 lookupCVE-2026-73251 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.3 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
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.
SSVC decision data
CVSS vector scores
1 official scoreWe 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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N——GitHub_MVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/cesanta/mongoose/security/advisories/GHSA-qj6j-2692-v2r8CVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/cesanta/mongoose/commit/2988bc9df3a5efc9539471cb7455975fa25df483CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/cesanta/mongoose/releases/tag/7.23CVE reference, GitHub_M · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Certificate Validation
Improper Certificate Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.