PT-2026-44997 · Exim · Exim

Sin99Xx + 1 · Published 2026-05-29 · Updated 2026-05-30 · CVE-2026-48840

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Name of the Vulnerable Software and Affected Versions Exim versions 4.88 through 4.99.3

Description In certain proxy configurations, the PROXY-protocol parser mishandles short payloads, resulting in a pre-authentication information disclosure. This issue allows the leakage of uninitialized stack memory values, specifically live userspace virtual address (VA) pointers, to a client. This can be used as a primitive to defeat Address Space Layout Randomization (ASLR), which is a security technique used to prevent exploitation by randomizing the memory addresses used by a process.

Recommendations Update to version 4.99.4.

Fix

Weakness Enumeration

CWE-839

Related Identifiers

CVE-2026-48840

Affected Products

Exim

References · 10

• https://nvd.nist.gov/vuln/detail/CVE-2026-48840 · Security Note
• https://twitter.com/oss_security/status/2060373425567252595 · Twitter Post
• https://reddit.com/r/cpanel/comments/1trdtx7/security_cve202648840_eximsecurity202605191 · Reddit Post
• https://openwall.com/lists/oss-security/2026/05/29/3 · Note
• https://reddit.com/r/mxroute/comments/1trm15w/new_exim_vuln_dropped_cve202648840 · Reddit Post
• https://exim.org/static/doc/security/EXIM-Security-2026-05-19.1 · Note
• http://openwall.com/lists/oss-security/2026/05/29/3 · Note
• https://twitter.com/infoflowcloud/status/2060840228139548846 · Twitter Post
• https://twitter.com/CVEnew/status/2060839329061085285 · Twitter Post
• https://twitter.com/sin99xx/status/2060665761757045033 · Twitter Post