CVE-2021-20255: debian debian_linux Loop with Unreachable Exit Condition
Vulnerability summary
CVE-2021-20255 is a medium (CVSS 5.5) Loop with Unreachable Exit Condition vulnerability in debian debian_linux. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 35.3% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 17 · Related 17Timeline
- 09-03-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
A stack overflow via an infinite recursion vulnerability was found in the eepro100 i8255x device emulator of QEMU. This issue occurs while processing controller commands due to a DMA reentry issue. This flaw allows a guest user or process to consume CPU cycles or crash the QEMU process on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
CVSS metrics
7 scores · 6 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · WolfiEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · ChainguardEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · AlpineEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.41%
Chance of exploitation in the next 30 days
Percentile
35%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.41% 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 cause- CWE-835Loop with Unreachable Exit ConditionThe product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
- CWE-674Uncontrolled RecursionThe product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Chainguard14 products
- qemu< 11.0.1-r0
- qemu-block-iscsi< 11.0.1-r0
- qemu-block-rbd< 11.0.1-r0
- qemu-edk2-aarch64< 11.0.1-r0
- qemu-edk2-x86_64< 11.0.1-r0
Wolfi14 products
- qemu< 11.0.1-r0
- qemu-block-iscsi< 11.0.1-r0
- qemu-block-rbd< 11.0.1-r0
- qemu-edk2-aarch64< 11.0.1-r0
- qemu-edk2-x86_64< 11.0.1-r0
Debian2 products
- qemuAll versions (No fix recorded) | < 1:8.1.0+ds-1
- debian_linuxEOL9.0
Ubuntu2 products
- qemuAll versions (No fix recorded)
- qemu-hweAll versions (No fix recorded)
Alpine1 product
- qemu< 6.0.0-r1
5 vendors · 33 products
References
11 links- bugzilla.redhat.com/show_bug.cgi?id=1930646X Refsource MISCFIXIssue TrackingPatchThird Party Advisory
- www.openwall.com/lists/oss-security/2021/02/25/1X Refsource MISCREPORTFIXMailing ListPatchThird Party Advisory
- ruhr-uni-bochum.sciebo.de/s/NNWP2GfwzYKeKwE?path=%2Feepro100_stackoverflow1X Refsource MISCREPORTAdvisoryThird Party Advisory
lists.debian.org/debian-lts-announce/2021/04/msg00009.htmlMailing ListX Refsource MLISTAdvisoryThird Party Advisory