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Fencer Vulns
high 8.2

CVE-2020-36323 json

In the standard library in Rust before 1.52.0, there is an optimization for joining strings that can cause uninitialized bytes to be expose…

published 2021-04-14 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-23862

cvss
8.2
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 81%
public exploits
0
none known

Summary

In the standard library in Rust before 1.52.0, there is an optimization for joining strings that can cause uninitialized bytes to be exposed (or the program to crash) if the borrowed string changes after its length is checked.

Patch / fix

  • rust-lang rust 1.52.0
  • rustc Debian 14, Debian 13, Debian 12 1.53.0+dfsg1-1

debian advisories DEBIAN-CVE-2020-36323

  • rustc Ubuntu 20.04 LTS 1.53.0+dfsg1+llvm-4ubuntu1~20.04.1
  • rustc Ubuntu 22.04 LTS 1.53.0+dfsg1+llvm-4ubuntu1

ubuntu advisories UBUNTU-CVE-2020-36323

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rls RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • rust RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • cargo RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • clippy RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • rustfmt RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • rust-gdb RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • rust-src RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9
  • rust-lldb RHEL 8 1.52.1-1.module+el8.4.0+11282+0729bac9

red hat advisories RHSA-2021:3063RHSA-2021:3042

  • rust Rocky Linux 8 1.52.1-1.module+el8.4.0+641+ca238f88
  • rust-toolset Rocky Linux 8 1.52.1-1.module+el8.4.0+641+ca238f88

rocky linux advisories RLSA-2021:3063

  • rust Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 1.51.0-r2
  • chromium-rust Alpine 3.24 1.51.0-r2

alpine advisories ALPINE-CVE-2020-36323

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • rust Arch Linux 1:1.52.0-1

arch linux advisories AVG-1801

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-36323 updated cvss 8.2

rust: optimization for joining strings can cause uninitialized bytes to be exposed

  • Red Hat Developer Tools for Red Hat Enterprise Linux Server (v. 7) rust-toolset-1.52 1.52.1-1.el7_9, rust-toolset-1.52-rls 1.52.1-2.el7_9, rust-toolset-1.52-rust 1.52.1-2.el7_9, rust-toolset-1.52-build 1.52.1-1.el7_9, rust-toolset-1.52-cargo 1.52.1-2.el7_9, rust-toolset-1.52-clippy 1.52.1-2.el7_9, +7 more
    fixed: vendor fix RHSA-2021:3042
  • Red Hat Enterprise Linux AppStream (v. 8) rls 1.52.1-1.module+el8.4.0+11282+0729bac9, rust 1.52.1-1.module+el8.4.0+11282+0729bac9, cargo 1.52.1-1.module+el8.4.0+11282+0729bac9, clippy 1.52.1-1.module+el8.4.0+11282+0729bac9, rustfmt 1.52.1-1.module+el8.4.0+11282+0729bac9, rust-gdb 1.52.1-1.module+el8.4.0+11282+0729bac9, +5 more
    fixed: vendor fix RHSA-2021:3063
  • Red Hat Enterprise Linux 9 rust, cargo, clippy, rustfmt, rust-gdb, rust-src, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.02% chance of exploitation in the next 30 days, higher than 81% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:N/A:P

Classification

Weakness
  • CWE-134 Use of Externally-Controlled Format String

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.