How severe is CVE-2026-59877?

CVE-2026-59877 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-59877 being actively exploited?

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

What products are affected by CVE-2026-59877?

CVE-2026-59877 affects Protobufjs Project Protobufjs. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59877?

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

When was CVE-2026-59877 published?

CVE-2026-59877 was published on 2026-07-08 and last updated on 2026-07-10.

CVE-2026-59877

CVE-2026-59877 is a medium-severity vulnerability in Protobufjs Project Protobufjs with a CVSS 3.x base score of 5.3. 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-835.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Protobufjs Project Protobufjs
Published: 2026-07-08
Last modified: 2026-07-10

Description

protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.6.5 and 8.6.6, protobufjs parsed option names by advancing through schema tokens until reaching an = token without checking for end of input, so a crafted .proto schema that opens an option declaration and ends prematurely can cause parse, Root.load, or Root.loadSync to loop indefinitely. This issue is fixed in versions 7.6.5 and 8.6.6.

Frequently asked questions

What is CVE-2026-59877?: protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.6.5 and 8.6.6, protobufjs parsed option names by advancing through schema tokens until reaching an = token without checking for end of input, so a crafted .proto schema that opens an option declaration and ends prematurely can cause parse, Root.load, or Root.loadSync to loop indefinitely. This issue is fixed in versions 7.6.5 and 8.6.6.
How severe is CVE-2026-59877?: CVE-2026-59877 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-59877 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59877?: CVE-2026-59877 affects Protobufjs Project Protobufjs. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59877?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-59877 published?: CVE-2026-59877 was published on 2026-07-08 and last updated on 2026-07-10.

References

Affected products (1)

cpe:2.3:a:protobufjs_project:protobufjs:*:*:*:*:*:node.js:*:*

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