An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1.

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• exim eximbefore 4.90.1

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2019-10149A flaw was found in Exim versions 4.87 to 4.91 (inclusive).KEV
  99Now
• CVE-2010-4344Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70 allows remote attackers to execute arbitrary code KEV
  91Now
• CVE-2019-16928Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than CVE-2019-15846.KEV
  81Now
• CVE-2010-4345Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of the exim user account to specify an alternate confiKEV
  66This week
• CVE-2025-26794Exim 4.98 before 4.98.1, when SQLite hints and ETRN serialization are used, allows remote SQL injection.
  62This week
• CVE-2020-28018Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.
  56Plan

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1char buf[256];2memcpy(buf, pkt->data, pkt->len);

1char buf[256];2if (pkt->len > sizeof(buf)) {3  return -EINVAL;4}5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.