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Fencer Vulns
high 7.5

CVE-2021-28875 json

In the standard library in Rust before 1.50.0, read_to_end() does not validate the return value from Read in an unsafe context.

published 2021-04-11 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-15528

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

In the standard library in Rust before 1.50.0, read_to_end() does not validate the return value from Read in an unsafe context. This bug could lead to a buffer overflow.

Patch / fix

  • rust-lang rust 1.50.0
  • rustc Debian 14, Debian 13, Debian 12 1.53.0+dfsg1-1

debian advisories DEBIAN-CVE-2021-28875

  • rustc Ubuntu 20.04 LTS 1.51.0+dfsg1+llvm-1~exp3ubuntu1~20.04.2

ubuntu advisories UBUNTU-CVE-2021-28875

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 Arch Linux 1:1.50.0-1

arch linux advisories AVG-1803

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-2021-28875 updated cvss 7.5

rust: heap-based buffer overflow in read_to_end() because it does not validate the return value from Read in an unsafe context

  • 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

2.12% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/rust-lang/rust/issues/80894 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

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.