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CVE-2026-35346

uutils coreutils comm Silent Data Corruption via Lossy UTF-8 Normalization

3.3 LowFix available

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

0.18%Up 0.2 points since Apr 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 3.3

uutils coreutils comm Silent Data Corruption via Lossy UTF-8 Normalization

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
CVE-2026-35346
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
EUVDEUVD-2026-24978 3.3

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
EUVD-2026-24978
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-6gcw-w7cp-94g9 3.3

comm: lossy UTF-8 conversion silently corrupts non-UTF-8 output

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Zellic finding 3.34. Reported in the Zellic uutils coreutils Program Security Assessment (for Canonical, Jan 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242.

Record
GHSA-6gcw-w7cp-94g9
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-116, CWE-176
Updated
2026-11-02
GitHub AdvisoriesGHSA-hwhf-8p2f-45wr 3.3

Duplicate Advisory: coreutils' comm utility silently corrupts data by performing lossy UTF-8 conversion on all output lines

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-6gcw-w7cp-94g9. This link is maintained to preserve external references.

Original Description

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
GHSA-hwhf-8p2f-45wr
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
NVD 3.3

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
CVE-2026-35346
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
OSV 3.3

uutils coreutils comm Silent Data Corruption via Lossy UTF-8 Normalization

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
CVE-2026-35346
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
Show 4 moreShow less
OSVDEBIAN-CVE-2026-35346 3.3

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
DEBIAN-CVE-2026-35346
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02
OSVGHSA-6gcw-w7cp-94g9 3.3

comm: lossy UTF-8 conversion silently corrupts non-UTF-8 output

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Zellic finding 3.34. Reported in the Zellic uutils coreutils Program Security Assessment (for Canonical, Jan 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242.

Record
GHSA-6gcw-w7cp-94g9
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-116, CWE-176
Updated
2026-11-02
OSVGHSA-hwhf-8p2f-45wr 3.3

Duplicate Advisory: coreutils' comm utility silently corrupts data by performing lossy UTF-8 conversion on all output lines

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-6gcw-w7cp-94g9. This link is maintained to preserve external references.

Original Description

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
GHSA-hwhf-8p2f-45wr
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness
CWE-176
Updated
2026-11-02
OSVUBUNTU-CVE-2026-35346 3.3

The comm utility in uutils coreutils silently corrupts data by performing lossy UTF-8 conversion on all output lines. The implementation uses String::from_utf8_lossy(), which replaces invalid UTF-8 byte sequences with the Unicode replacement character (U+FFFD). This behavior differs from GNU comm, which processes raw bytes and preserves the original input. This results in corrupted output when the utility is used to compare binary files or files using non-UTF-8 legacy encodings.

Record
UBUNTU-CVE-2026-35346
CVSS 3.1
3.3 LowCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
uu_comm
crates.io
 before 0.6.0
0.6.0
rust-coreutils
Debian:12
 All versions, plus listed versions
0.0.17-20.0.17-30.0.17-40.0.17-50.0.17-6
Show 39 moreShow less
0.0.19-10.0.19-20.0.19-30.0.20-10.0.21-10.0.22-10.0.23-10.0.23-20.0.23-30.0.24-10.0.24-20.0.26-10.0.26-20.0.26-30.0.26-40.0.26-50.0.27-10.0.27-20.0.27-30.0.30-10.0.30-20.0.30-30.0.30-3~exp10.0.30-40.10.0-10.11.0-10.11.0-20.12.0-10.6.0-10.7.0-10.8.0-10.8.0-20.8.0-30.8.0-40.8.0-50.8.0-60.9.0-10.9.0-20.9.0-3
 None known
rust-coreutils
Debian:13
 All versions, plus listed versions
0.0.30-20.0.30-30.0.30-3~exp10.0.30-40.10.0-1
Show 14 moreShow less
0.11.0-10.11.0-20.12.0-10.6.0-10.7.0-10.8.0-10.8.0-20.8.0-30.8.0-40.8.0-50.8.0-60.9.0-10.9.0-20.9.0-3
 None known
rust-coreutils
Debian:14
 before 0.6.0-1, plus listed versions
0.0.30-20.0.30-30.0.30-3~exp10.0.30-4
0.6.0-1
rust-coreutils
Ubuntu:24.04:LTS
 All versions, plus listed versions
0.0.20-10.0.22-10.0.23-10.0.23-20.0.23-30.0.24-10.0.24-2
 None known
rust-coreutils
Ubuntu:25.10
 All versions, plus listed versions
0.0.30-10.0.30-20.0.30-2ubuntu20.1.0-0ubuntu10.1.0+git20250711.2ba3a33-0ubuntu1
Show 11 moreShow less
0.1.0+git20250711.2ba3a33-0ubuntu20.1.0+git20250711.2ba3a33-0ubuntu30.1.0+git20250711.2ba3a33-0ubuntu40.1.0+git20250801.cf79675-0ubuntu10.1.0+git20250813.4af2a84-0ubuntu20.1.0+git20250813.4af2a84-0ubuntu40.1.0+git20250813.4af2a84-0ubuntu60.1.0+git20250813.4af2a84-0ubuntu70.2.2-0ubuntu10.2.2-0ubuntu20.2.2-0ubuntu2.1
 None known

History

History
RecordedChangedSources
affected
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

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

In short

CVE-2026-35346 is a low vulnerability (CVSS 3.3) in Uutils Coreutils, published April 22, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. Fixed in uu_comm 0.6.0.

References

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