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No exploitation reportedFix available

CVE-2020-15254

No exploitation reported by the sources we read.

  • Published2020-10-16
  • Fixed in0.4.4
  • WeaknessCWE-119 · CWE-401

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Crossbeam is a set of tools for concurrent programming. In crossbeam-channel before version 0.4.4, the bounded channel incorrectly assumes that `Vec::from_iter` has allocated capacity that same as the number of iterator elements. `Vec::from_iter` does not actually guarantee that and may allocate extra memory. The destructor of the `bounded` channel reconstructs `Vec` from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when `Vec::from_iter` has allocated different sizes with the number of iterator elements. This has been fixed in crossbeam-channel 0.4.4.

Timeline

dates in UTC
  1. 2020-10-1617:15CVE publishedNVD

Versions per branch

NVD · OSV
Crossbeam project crossbeam
BranchAffectedFixed in
0.4< 0.4.40.4.4
0.4≥ 0.4.3, < 0.4.40.4.4

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • firefoxUbuntu:20.04:LTSall versions · fixed in 82.0+build2-0ubuntu0.20.04.1
  • firefoxUbuntu:18.04:LTSall versions · fixed in 82.0+build2-0ubuntu0.18.04.1
  • firefoxUbuntu:16.04:LTSall versions · fixed in 82.0+build2-0ubuntu0.16.04.5
  • firefoxCleanStartall versions · fixed in 82.0-r0and 1 other package
  • firefoxAlpine:v3.23all versions · fixed in 82.0-r0and 1 other package
  • firefoxAlpine:v3.22all versions · fixed in 82.0-r0and 1 other package
  • firefoxAlpine:v3.21all versions · fixed in 82.0-r0and 1 other package
  • firefoxAlpine:v3.20all versions · fixed in 82.0-r0

18 more package ranges on OSV.dev

Vendor advisories

  • CVE-2020-15254 Red Hat Product Security

    Mozilla: Undefined behavior in bounded channel of crossbeam rust crate

Full record on NVD

Fix

  1. Update Crossbeam project crossbeam to 0.4.4

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.18.1known since 2026-10-23
  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • CNAweakness (CWE)CWE-119known since 2026-10-23
  • NVDweakness (CWE)CWE-401read 2026-10-23
  • FIRST EPSSEPSS score2.7 %2026-11-08
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryHIGH2021-08-19

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2020-10-16
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-m8h8-v6jh-c762 GHSA-v5m7-53cv-f3hx

Frequently asked questions

What is CVE-2020-15254?

Crossbeam is a set of tools for concurrent programming. In crossbeam-channel before version 0.4.4, the bounded channel incorrectly assumes that `Vec::from_iter` has allocated capacity that same as the number of iterator elements. `Vec::from_iter` does not actually guarantee that and may allocate extra memory. The destructor of the `bounded` channel reconstructs `Vec` from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when `Vec::from_iter` has allocated different sizes with the number of iterator elements. This has been fixed in crossbeam-channel 0.4.4.

Is CVE-2020-15254 actively exploited?

Active exploitation of CVE-2020-15254 has not been confirmed. Its EPSS score was 2.7% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-15254?

CVE-2020-15254 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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