How severe is CVE-2023-29421?

CVE-2023-29421 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-29421 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-29421?

CVE-2023-29421 affects Bzip3 Project Bzip3. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-29421?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-29421 published?

CVE-2023-29421 was published on 2023-04-06 and last updated on 2026-06-17.

CVE-2023-29421

CVE-2023-29421 is a high-severity vulnerability in Bzip3 Project Bzip3 with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Bzip3 Project Bzip3
Published: 2023-04-06
Last modified: 2026-06-17

Description

An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is an out-of-bounds write in bz3_decode_block.

Frequently asked questions

What is CVE-2023-29421?: An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is an out-of-bounds write in bz3_decode_block.
How severe is CVE-2023-29421?: CVE-2023-29421 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-29421 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-29421?: CVE-2023-29421 affects Bzip3 Project Bzip3. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-29421?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-29421 published?: CVE-2023-29421 was published on 2023-04-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:bzip3_project:bzip3:*:*:*:*:*:*:*:*

More vulnerabilities in Bzip3 Project Bzip3

CVE-2023-29420 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is a crash caused by an invalid memmove in…
CVE-2023-29419 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is a bz3_decode_block out-of-bounds read.
CVE-2023-29418 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is an xwrite out-of-bounds read.
CVE-2023-29417 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 1.2.2. There is a bz3_decompress out-of-bounds read in certain…
CVE-2023-29416 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 before 1.3.0. A bz3_decode_block out-of-bounds write can occur with a…
CVE-2023-29415 — Medium (CVSS 6.5): An issue was discovered in libbzip3.a in bzip3 before 1.3.0. A denial of service (process hang) can occur with a…

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