CVE-2026-59877

mediumCVSS 5.3covered by 1 sourcefirst seen 2026-07-08

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.

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Exploitation outlook

Low exploitation risk0.33% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 25% of all EPSS-scored CVEs.

Advisory coverage (1)

mediumCVE-2026-59877: protobufjs compiles protobuf definitions into JavaScript (JS) functions. Prior to 7.6.5 and 8.…nvd · 2026-07-08

External references

NVD record for CVE-2026-59877

CVE.org record

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