CVE-2019-18420: debian debian_linux
Vulnerability summary
CVE-2019-18420 is a medium (CVSS 6.5) vulnerability in debian debian_linux. EPSS estimates a 2.91% chance of exploitation in the next 30 days, higher than 87% of scored vulnerabilities.
Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 10 · Related 8Timeline
- 31-10-2019PublishedVulnerability first disclosed.
- 05-08-2024Last modifiedVulnerability information updated.
Description
An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to cause a denial of service via a VCPUOP_initialise hypercall. hypercall_create_continuation() is a variadic function which uses a printf-like format string to interpret its parameters. Error handling for a bad format character was done using BUG(), which crashes Xen. One path, via the VCPUOP_initialise hypercall, has a bad format character. The BUG() can be hit if VCPUOP_initialise executes for a sufficiently long period of time for a continuation to be created. Malicious guests may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen versions 4.6 and newer are vulnerable. Xen versions 4.5 and earlier are not vulnerable. Only x86 PV guests can exploit the vulnerability. HVM and PVH guests, and guests on ARM systems, cannot exploit the vulnerability.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
2.91%
Chance of exploitation in the next 30 days
Percentile
87%
Versus all other CVEs
30-day change
Increase +0.39 pp
From 2.52% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian2 products
- xen< 4.11.3+24-g14b62ab3e5-1
- debian_linuxEOL9.0 | 10.0
Alpine1 product
- xen< 4.11.2-r0
Fedoraproject1 product
- fedoraEOL29 | 30 | 31
Ubuntu1 product
- xenAll versions (No fix recorded)
Xen1 product
- xen≤ 4.12.1
5 vendors · 6 products
References
14 links- www.openwall.com/lists/oss-security/2019/10/31/1Mailing ListX Refsource MLISTREPORTPatchThird Party Advisory
- lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.htmlVendor AdvisoryX Refsource SUSEBroken LinkMailing ListThird Party Advisory
