How severe is CVE-2025-55398?

CVE-2025-55398 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2025-55398 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-55398?

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

Does CVE-2025-55398 have an EU (EUVD) identifier?

Yes. CVE-2025-55398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25611.

When was CVE-2025-55398 published?

CVE-2025-55398 was published on 2025-08-22 and last updated on 2026-06-17.

CVE-2025-55398

CVE-2025-55398 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. 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-1284.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-25611
Weakness: CWE-1284
Published: 2025-08-22
Last modified: 2026-06-17

Description

An issue was discovered in mouse07410 asn1c thru 0.9.29 (2025-03-20) - a fork of vlm asn1c. In UPER (Unaligned Packed Encoding Rules), asn1c-generated decoders fail to enforce INTEGER constraints when the bound is positive and exceeds 32 bits in length, potentially allowing incorrect or malicious input to be processed.

Frequently asked questions

What is CVE-2025-55398?: An issue was discovered in mouse07410 asn1c thru 0.9.29 (2025-03-20) - a fork of vlm asn1c. In UPER (Unaligned Packed Encoding Rules), asn1c-generated decoders fail to enforce INTEGER constraints when the bound is positive and exceeds 32 bits in length, potentially allowing incorrect or malicious input to be processed.
How severe is CVE-2025-55398?: CVE-2025-55398 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2025-55398 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-55398?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-55398 have an EU (EUVD) identifier?: Yes. CVE-2025-55398 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25611.
When was CVE-2025-55398 published?: CVE-2025-55398 was published on 2025-08-22 and last updated on 2026-06-17.

References

https://github.com/mouse07410/asn1c/issues/222

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