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Fencer Vulns
medium 6.5

CVE-2023-24626 json

socket.c in GNU Screen through 4.9.0, when installed setuid or setgid (the default on platforms such as Arch Linux and FreeBSD), allows loc…

published 2023-04-08 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-28637

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits
1
Exploit-DB

Summary

socket.c in GNU Screen through 4.9.0, when installed setuid or setgid (the default on platforms such as Arch Linux and FreeBSD), allows local users to send a privileged SIGHUP signal to any PID, causing a denial of service or disruption of the target process.

Patch / fix

  • screen Debian 14, Debian 13 4.9.1-1

debian advisories DEBIAN-CVE-2023-24626

  • screen Ubuntu 22.04 LTS 4.9.0-1ubuntu0.1
  • screen Ubuntu Pro 14.04 LTS 4.1.0~20120320gitdb59704-9ubuntu0.1~esm3
  • screen Ubuntu Pro 16.04 LTS 4.3.1-2ubuntu0.1+esm1
  • screen Ubuntu Pro 18.04 LTS 4.6.2-1ubuntu1.1+esm1

ubuntu advisories UBUNTU-CVE-2023-24626

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • screen openSUSE Tumbleweed 4.9.1-1.1

opensuse advisories openSUSE-SU-2024:13285-1

  • screen Alpine 3.15 4.8.0-r6
  • screen Alpine 3.17, Alpine 3.16 4.9.0-r1
  • screen Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 4.9.0-r3

alpine advisories ALPINE-CVE-2023-24626

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • screen CBL-Mariner 2.0 4.9.1-1

azure linux advisories AZL-26216

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-24626 updated cvss 6.5

screen: allows sending SIGHUP to arbitrary PIDs

  • Red Hat Enterprise Linux 6 screen Red Hat Enterprise Linux 7 screen
    affected: no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (EDB-51252)
  2. Published

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-51252 GNU screen v4.9.0 - Privilege Escalation local, 2023-04-05

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
CNA 3.1 6.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Classification

Weakness
  • CWE-732 Incorrect Permission Assignment for Critical Resource

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.