CVE-2021-20257: debian debian_linux Loop with Unreachable Exit Condition
Vulnerability summary
CVE-2021-20257 is a medium (CVSS 6.5) Loop with Unreachable Exit Condition vulnerability in debian debian_linux. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 30.9% of scored vulnerabilities.
Not severe (CVSS 6.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 29 · Related 26Timeline
- 16-03-2022PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
- OSV · AlpineEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
EPSS trend
Probability
0.37%
Chance of exploitation in the next 30 days
Percentile
31%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.37% 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: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Redhat5 products
Debian2 products
- qemu< 1:5.2+dfsg-9
- debian_linuxEOL10.0
Alpine1 product
- qemu< 6.1.1-r0
Fedoraproject1 product
- fedoraEOL33
Qemu1 product
- qemu< 6.2.0
Ubuntu1 product
- qemu< 2.0.0+dfsg-2ubuntu1.47+esm6 | < 1:2.5+dfsg-5ubuntu10.51+esm4 | < 1:2.11+dfsg-1ubuntu7.37 | < 1:4.2-3ubuntu6.17
6 vendors · 11 products
References
15 links- www.openwall.com/lists/oss-security/2021/02/25/2X Refsource MISCREPORTMailing ListPatchThird Party Advisory
- lists.gnu.org/archive/html/qemu-devel/2021-02/msg07428.htmlX Refsource MISCMailing ListPatchVendor Advisory
- github.com/qemu/qemu/commit/3de46e6fc489c52c9431a8a832ad8170a7569bd8X Refsource MISCPatchThird Party Advisory
lists.debian.org/debian-lts-announce/2022/09/msg00008.htmlMailing ListX Refsource MLISTThird Party Advisory
