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Fencer Vulns
critical 9.8

CVE-2020-15350 json

RIOT 2020.04 has a buffer overflow in the base64 decoder.

published 2020-07-07 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-7347

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

RIOT 2020.04 has a buffer overflow in the base64 decoder. The decoding function base64_decode() uses an output buffer estimation function to compute the required buffer capacity and validate against the provided buffer size. The base64_estimate_decode_size() function calculates the expected decoded size with an arithmetic round-off error and does not take into account possible padding bytes. Due to this underestimation, it may be possible to craft base64 input that causes a buffer overflow.

Patch / fix

Exploit prediction

1.47% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
  • CWE-131 Incorrect Calculation of Buffer Size

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.