The swap_char2b function in X.Org X Font Server (xfs) before 1.0.5 allows context-dependent attackers to execute arbitrary code via (1) QueryXBitmaps and (2) QueryXExtents protocol requests with crafted size values that specify an arbitrary number of bytes to be swapped on the heap, which triggers heap corruption.
Conclusion & alert: CVE-2007-4990 is rated High Risk (68.3/100): CVSS High severity, with high exploitation likelihood (EPSS 10.74%, 95th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +5.31% over the last day, indicating growing attacker interest. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 5.43% | 10.74% | +5.31% |
| 2 | 2026-05-24 | 5.23% | 5.43% | +0.20% |
| 3 | 2026-04-12 | — | 5.23% | — |
Full EPSS history (17 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 2.0 | HIGH |
|
10.0 | 6.4 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
gentoo
|
high | CVE-2007-4990: 1 GLSA(s) (200710-11), 1 atom(s) (x11-apps/xfs); latest impact high. | https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2007-4990 |
redhat
|
low | — | https://access.redhat.com/security/cve/CVE-2007-4990 |
ubuntu
|
medium | CVE-2007-4990 medium priority: Ubuntu including 1 source packages (xfs), 9 status rows across 9 suites (dapper, edgy, feisty, gutsy, hardy, intrepid, jaunty, karmic, upstream): ignored 4, not-affected 4, released 1. | https://ubuntu.com/security/CVE-2007-4990 |
Red Hat is aware of this issue and is tracking it via the following bug: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=CVE-2007-4990 The Red Hat Security Response Team has rated this issue as having low security impact, a future update may address this flaw.
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| x.org | x_font_server | <= 1.0.4 | cpe:2.3:a:x.org:x_font_server:*:*:*:*:*:*:*:* |