Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | screen | 4.9.1-1 | — |
| Debian 13 | screen | 4.9.1-1 | — |
| Debian 12 | screen | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | screen | 4.9.1-1ubuntu1 | USN-7978-1 |
| Ubuntu 22.04 LTS | screen | 4.9.0-1ubuntu0.1 | USN-7978-1 |
| Ubuntu 20.04 LTS | screen | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | screen | 4.6.2-1ubuntu1.1+esm1 | USN-6198-1 |
| Ubuntu Pro 16.04 LTS | screen | 4.3.1-2ubuntu0.1+esm1 | USN-6198-1 |
| Ubuntu Pro 14.04 LTS | screen | 4.1.0~20120320gitdb59704-9ubuntu0.1~esm3 | USN-6198-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | screen | 4.9.1-1.1 | openSUSE-SU-2024:13285-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | screen | 4.9.0-r3 | — |
| Alpine v3.23 | screen | 4.9.0-r3 | — |
| Alpine v3.22 | screen | 4.9.0-r3 | — |
| Alpine v3.21 | screen | 4.9.0-r3 | — |
| Alpine v3.20 | screen | 4.9.0-r3 | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | screen | 4.9.0-r3 | — |
| Alpine v3.18 | screen | 4.9.0-r3 | — |
| Alpine v3.17 | screen | 4.9.0-r1 | — |
| Alpine v3.16 | screen | 4.9.0-r1 | — |
| Alpine v3.15 | screen | 4.8.0-r6 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | screen | 4.8.0-5.amzn2023.0.3 | ALAS2023-2023-224 |
| Amazon Linux 2 | screen | 4.1.0-0.27.20120314git3c2946.amzn2.0.1 | ALAS2-2023-2023 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | screen | 4.9.1-1 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- GNU screen v4.9.0 - Privilege Escalation EDB-51252 · local · Apr 5, 2023
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 5
- USN-6198-1 screen vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-7978-1 screen vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- openSUSE-SU-2024:13285-1 screen-4.9.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2023-2023-224 Low: screen security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jun 27, 2023
- ALAS2-2023-2023 Low: screen security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · May 2, 2023