RUSTSEC-2026-0301

Vulnerability from osv_rustsec – Published: 2026-09-22 12:00 – Updated: 2026-09-22 20:47 – Source website
VLAI
Summary
Double free in `StackVec::retain` when a predicate or element `Drop` panics
Details

Summary

StackVec::retain committed its new length to self.len only after its internal loop completed. If the retain predicate or a removed element's Drop implementation panicked before the loop finished, unwinding proceeded with self.len still equal to the original, pre-retain length, leaving either a duplicated or already-destroyed element inside 0..len. StackVec's own Drop then revisited that slot, causing a double-drop (and for heap-owning types, a double-free).

Impact

Affects StackVec<T, CAP>::retain for T: Drop types where the predicate or the removed element's destructor can panic, on builds with unwinding enabled (panic = "unwind"). no_std/panic = "abort" builds cannot trigger this, since unwinding never occurs.

Patch

Fixed in 0.3.3 using an unwind-safe backshift guard, matching the approach alloc::vec::Vec::retain uses.

References
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "memory-corruption"
        ],
        "cvss": null,
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "stack_collections",
        "purl": "pkg:cargo/stack_collections"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.3.0"
            },
            {
              "fixed": "0.3.3"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "## Summary\n\n`StackVec::retain` committed its new length to `self.len` only after\nits internal loop completed. If the retain predicate or a removed\nelement\u0027s `Drop` implementation panicked before the loop finished,\nunwinding proceeded with `self.len` still equal to the original,\npre-retain length, leaving either a duplicated or already-destroyed\nelement inside `0..len`. `StackVec`\u0027s own `Drop` then revisited that\nslot, causing a double-drop (and for heap-owning types, a double-free).\n\n## Impact\n\nAffects `StackVec\u003cT, CAP\u003e::retain` for `T: Drop` types where the\npredicate or the removed element\u0027s destructor can panic, on builds\nwith unwinding enabled (`panic = \"unwind\"`). `no_std`/`panic = \"abort\"`\nbuilds cannot trigger this, since unwinding never occurs.\n\n## Patch\n\nFixed in 0.3.3 using an unwind-safe backshift guard, matching the\napproach `alloc::vec::Vec::retain` uses.",
  "id": "RUSTSEC-2026-0301",
  "modified": "2026-09-22T20:47:48Z",
  "published": "2026-09-22T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/stack_collections"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0301.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/OverwrittenCode/stack_collections/pull/4"
    }
  ],
  "related": [],
  "severity": [],
  "summary": "Double free in `StackVec::retain` when a predicate or element `Drop` panics"
}



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