How severe is CVE-2021-33641?

CVE-2021-33641 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-33641 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33641?

CVE-2021-33641 affects Openeuler Byacc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33641?

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-2021-33641 published?

CVE-2021-33641 was published on 2023-01-20 and last updated on 2026-06-17.

CVE-2021-33641

CVE-2021-33641 is a high-severity vulnerability in Openeuler Byacc with a CVSS 3.x base score of 7.8. 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-416.

Key facts

Severity: High (CVSS 3.x base score 7.8)
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Openeuler Byacc
Published: 2023-01-20
Last modified: 2026-06-17

Description

When processing files, malloc stores the data of the current line. When processing comments, malloc incorrectly accesses the released memory (use after free).

Frequently asked questions

What is CVE-2021-33641?: When processing files, malloc stores the data of the current line. When processing comments, malloc incorrectly accesses the released memory (use after free).
How severe is CVE-2021-33641?: CVE-2021-33641 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-33641 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33641?: CVE-2021-33641 affects Openeuler Byacc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33641?: 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-2021-33641 published?: CVE-2021-33641 was published on 2023-01-20 and last updated on 2026-06-17.

References

https://gitee.com/src-openeuler/byacc/commit/50225f48c6b53e9d7c936681a06682404cb8ec4d

Affected products (1)

cpe:2.3:a:openeuler:byacc:*:*:*:*:*:*:*:*

More vulnerabilities in Openeuler Byacc

CVE-2021-33642 — Medium (CVSS 5.5): When a file is processed, an infinite loop occurs in next_inline() of the more_curly() function.

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Other CWE-416 (Use After Free) vulnerabilities

CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

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