Security readout for executives and security teams
Plain-English summary
A malicious Rust package release can run attacker-controlled code while software is being compiled. Organizations that built projects using append-only-vec 0.1.9 may have exposed developer machines or CI systems, including credentials and build artifacts accessible from those systems.
Executive priority
Treat this as an immediate software-supply-chain incident assessment. Pause affected builds, determine whether version 0.1.9 executed, and protect CI credentials and release integrity. Escalate confirmed execution to incident response; evidence of downstream compromise remains incomplete.
Technical view
CVE-2026-77650 affects append-only-vec 0.1.9. The crate contains a rogue dependency that registers with a command-and-control server and enables arbitrary code execution during compilation. The supplied record assigns CVSS 3.1 score 9.8 and CWE-506. Other versions are not identified as affected.
Likely exposure
Exposure is limited to environments that fetched and compiled append-only-vec 0.1.9, directly or transitively. CI runners, developer workstations, dependency caches, and builds using lockfiles should be reviewed. The bundle provides no affected-download counts or confirmed victim scope.
Exploitation context
The described package behavior is intentionally malicious and contacts command-and-control infrastructure. However, the source bundle marks the CVE as absent from KEV and provides no confirmed victim compromises. Do not equate package availability or compilation with proven successful follow-on exploitation.
Researcher notes
The documented trigger is compilation rather than ordinary runtime use. Analysis should distinguish dependency presence, package download, compilation, command-and-control contact, and successful code execution. No command-and-control indicators, patch version, or complete forensic guidance are included in the supplied bundle.
Mitigation direction
- Immediately stop builds that resolve append-only-vec 0.1.9.
- Remove or block version 0.1.9 from dependency resolution and caches.
- Isolate potentially affected build hosts pending investigation.
- Check Rust and crate-maintainer guidance for the supported replacement or remediation.
- Rotate exposed credentials if investigation indicates compromise.
Validation and detection
- Search manifests and lockfiles for append-only-vec version 0.1.9.
- Identify CI jobs and developer systems that compiled the affected dependency.
- Review build-time process and network telemetry for anomalous activity.
- Inspect dependency caches and previously produced artifacts for affected builds.
- Confirm rebuilt projects no longer resolve version 0.1.9.
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-506: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-77650 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
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9mitreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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://blog.rust-lang.org/2026/08/20/supply-chain-attack-on-arrayrefCVE reference, mitre
- https://github.com/rustsec/advisory-db/issues/3161CVE reference, mitre
- https://www.stepsecurity.io/blog/arrayref-rust-crate-supply-chain-attackCVE reference, mitre
- https://safedep.io/arrayref-proc-macro1-rust-build-time-malware/CVE reference, mitre
- https://rustsec.org/advisories/RUSTSEC-2026-0262.htmlCVE reference, mitre
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.
Embedded Malicious Code
Embedded Malicious Code represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.