Security readout for executives and security teams
Plain-English summary
A Rust RSA library can crash when asked to build a private key whose prime value is 1. This is a low-severity availability issue, not a confidentiality or integrity break in the published record. Organizations should prioritize it where applications accept or process untrusted RSA key material.
Executive priority
Treat as routine but timely dependency maintenance. Escalate priority for internet-facing or multi-tenant services that process user-supplied RSA key material, because a crash could translate into service disruption.
Technical view
RustCrypto rsa crate versions before 0.9.10 panic instead of returning an error during RSA private key construction from components when one prime equals 1. The issue is classified as CWE-703 and fixed in version 0.9.10. CVSS 4.0 score is 2.7, with low availability impact only.
Likely exposure
Exposure is likely limited to Rust applications using the RustCrypto rsa crate below 0.9.10 that construct private keys from components, especially if key components can be supplied by users, files, APIs, or other untrusted inputs.
Exploitation context
The sources do not report active exploitation, and the CVE is not marked KEV. A successful trigger would cause a panic, potentially affecting service availability depending on how the application handles Rust panics.
Researcher notes
The available record is narrow: panic on prime value 1 during private key construction from components. No exploit evidence, broader impact, or affected downstream products are provided. Analysis should focus on dependency reachability and whether untrusted key components reach this API.
Mitigation direction
- Upgrade the RustCrypto rsa crate to version 0.9.10 or later.
- Identify applications that parse or construct RSA private keys from external components.
- Check the GitHub advisory for any updated vendor guidance.
- Review panic handling around key parsing and private key construction paths.
Validation and detection
- Inventory Cargo.lock and dependency manifests for rsa versions below 0.9.10.
- Confirm whether affected code calls RSA private key construction from components.
- Determine whether key components can originate from untrusted input.
- Verify updated builds resolve rsa to version 0.9.10 or later.
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-703: 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 lookupCVE-2026-21895 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
- Low
- CVSS
- 2.7 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
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.
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:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
2.7LowVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/RustCrypto/RSA/security/advisories/GHSA-9c48-w39g-hm26CVE reference · x_refsource_CONFIRM
- https://github.com/RustCrypto/RSA/commit/2926c91bef7cb14a7ccd42220a698cf4b1b692f7CVE reference · 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 Check or Handling of Exceptional Conditions
Improper Check or Handling of Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.