How severe is CVE-2021-33455?

CVE-2021-33455 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-33455 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33455?

CVE-2021-33455 affects Tortall Yasm. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-33455?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-33455 published?

CVE-2021-33455 was published on 2022-07-26 and last updated on 2026-06-17.

CVE-2021-33455

CVE-2021-33455 is a medium-severity vulnerability in Tortall Yasm with a CVSS 3.x base score of 5.5. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Tortall Yasm
Published: 2022-07-26
Last modified: 2026-06-17

Description

An issue was discovered in yasm version 1.3.0. There is a NULL pointer dereference in do_directive() in modules/preprocs/nasm/nasm-pp.c.

Frequently asked questions

What is CVE-2021-33455?: An issue was discovered in yasm version 1.3.0. There is a NULL pointer dereference in do_directive() in modules/preprocs/nasm/nasm-pp.c.
How severe is CVE-2021-33455?: CVE-2021-33455 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-33455 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33455?: CVE-2021-33455 affects Tortall Yasm. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-33455?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-33455 published?: CVE-2021-33455 was published on 2022-07-26 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:tortall:yasm:1.3.0:*:*:*:*:*:*:*

More vulnerabilities in Tortall Yasm

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CVE-2023-31972 — Medium (CVSS 5.5): yasm v1.3.0 was discovered to contain a use after free via the function pp_getline at /nasm/nasm-pp.c. Note: Multiple…
CVE-2021-33468 — Medium (CVSS 5.5): An issue was discovered in yasm version 1.3.0. There is a use-after-free in error() in modules/preprocs/nasm/nasm-pp.c.
CVE-2021-33467 — Medium (CVSS 5.5): An issue was discovered in yasm version 1.3.0. There is a use-after-free in pp_getline() in…

All CVEs affecting Tortall Yasm →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

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