CVE-2021-28877

In the standard library in Rust before 1.51.0, the Zip implementation calls __iterator_get_unchecked() for the same index more than once when nested. This bug can lead to a memory safety violation due to an unmet safety requirement for the TrustedRandomAccess trait.

Published: 2021-04-11 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-28877 is rated Moderate Risk (47.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.27%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-28877

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-05 0.50% 0.27% -0.22%
2 2025-11-21 0.27% 0.50% +0.22%
3 2025-11-18 — 0.27% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28877

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-28877

OS Trackers for CVE-2021-28877

vendor priority summary link
alpine high CVE-2021-28877: 1 source package rows (rust); 12 state rows across 6 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-community, edge-main); fixed 0, open 12. https://security.alpinelinux.org/vuln/CVE-2021-28877
debian not yet assigned CVE-2021-28877 not yet assigned priority: Debian including 1 source packages (rustc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2021-28877
gentoo normal CVE-2021-28877: 1 GLSA(s) (202210-09), 2 atom(s) (dev-lang/rust, dev-lang/rust-bin); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-28877
redhat medium — https://access.redhat.com/security/cve/CVE-2021-28877
suse high CVE-2021-28877 severity important: SUSE including 46 source package names (cargo, cargo-1.52.1-1.module+el8.4.0+11282+0729bac9, …), 151 product×package rows across 23 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (23 product lines)): Known Not Affected 137, Fixed 14. https://www.suse.com/security/cve/CVE-2021-28877/
ubuntu medium CVE-2021-28877 medium priority: Ubuntu including 1 source packages (rustc), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 5, ignored 4, DNE 3, needed 2, released 2. https://ubuntu.com/security/CVE-2021-28877

Affected software / configurations for CVE-2021-28877

Vendor Product Version Raw CPE
rust-lang rust < 1.51.0 cpe:2.3:a:rust-lang:rust:*:*:*:*:*:*:*:*

References for CVE-2021-28877

URL Tags
https://github.com/rust-lang/rust/pull/80670 Issue Tracking Patch Third Party Advisory
https://security.gentoo.org/glsa/202210-09 Third Party Advisory
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