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CVE-2021-26305

Read of uninitialized memory in cdr

9.8 CriticalFix available

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

1.71%Up 1.3 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 9.8

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
CVE-2021-26305
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-908
Updated
2026-11-02
CVE List No score

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
CVE-2021-26305
Updated
2026-11-02
EUVDEUVD-2021-1535 No score

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
EUVD-2021-1535
Updated
2026-11-03
GitHub AdvisoriesGHSA-37jj-wp7g-7wj4 9.8

Read of uninitialized memory in cdr

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
GHSA-37jj-wp7g-7wj4
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-908
Updated
2026-11-02
OSV 9.8

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
CVE-2021-26305
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-37jj-wp7g-7wj4 9.8

Read of uninitialized memory in cdr

An issue was discovered in Deserializer::read_vec in the cdr crate before 0.2.4 for Rust. A user-provided Read implementation can gain access to the old contents of newly allocated heap memory, violating soundness.

Record
GHSA-37jj-wp7g-7wj4
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-908
Updated
2026-11-02
OSVRUSTSEC-2021-0012 9.8

Reading uninitialized memory can cause UB (`Deserializer::read_vec`)

Deserializer::read_vec() created an uninitialized buffer and passes it to a user-provided Read implementation (Deserializer.reader.read_exact()).

Passing an uninitialized buffer to an arbitrary Read implementation is currently defined as undefined behavior in Rust. Official documentation for the Read trait explains the following: "It is your responsibility to make sure that buf is initialized before calling read. Calling read with an uninitialized buf (of the kind one obtains via MaybeUninit<T>) is not safe, and can lead to undefined behavior."

The flaw was corrected in commit ce310f7 by zero-initializing the newly allocated buffer before handing it to Deserializer.reader.read_exact().

Record
RUSTSEC-2021-0012
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
cdr
crates.io
before 0.2.4
0.2.4
cdr
crates.io
0.0.0-0 up to 0.2.4
0.2.4

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-26305 is a critical vulnerability (CVSS 9.8) in Cdr Project Cdr, published January 2, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.71%, the 77th percentile. Fixed in cdr 0.2.4.

References

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