Headline
CVE-2021-26937: security - screen crash processing combining characters
encoding.c in GNU Screen through 4.8.0 allows remote attackers to cause a denial of service (invalid write access and application crash) or possibly have unspecified other impact via a crafted UTF-8 character sequence.
- Products
- Openwall GNU/*/Linux server OS
- Linux Kernel Runtime Guard
- John the Ripper password cracker
- Free & Open Source for any platform
- in the cloud
- Pro for Linux
- Pro for macOS
- Wordlists for password cracking
- passwdqc policy enforcement
- Free & Open Source for Unix
- Pro for Windows (Active Directory)
- yescrypt KDF & password hashing
- yespower Proof-of-Work (PoW)
- crypt_blowfish password hashing
- phpass ditto in PHP
- tcb better password shadowing
- Pluggable Authentication Modules
- scanlogd port scan detector
- popa3d tiny POP3 daemon
- blists web interface to mailing lists
- msulogin single user mode login
- php_mt_seed mt_rand() cracker
- Services
- Publications
- Articles
- Presentations
- Resources
- Mailing lists
- Community wiki
- Source code repositories (GitHub)
- Source code repositories (CVSweb)
- File archive & mirrors
- How to verify digital signatures
- OVE IDs
- What’s new
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date: Tue, 9 Feb 2021 16:06:07 -0000 (UTC) From: Tavis Ormandy <taviso@…il.com> To: oss-security@…ts.openwall.com Subject: screen crash processing combining characters
Hello, I noticed someone posted this to the screen-devel list. I can reproduce it here, just catting the testcase does crash my screen session.
https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html
(I think it wasn’t supposed to be public, but it is, so better it’s visible to security teams)
It looks like it might be exploitable at first glance, I see a crash here in encoding.c, because i is out of range.
1411 else if (!combchars[i]) 1412 { 1413 combchars[i] = (struct combchar *)malloc(sizeof(struct combchar)); 1414 if (!combchars[i]) 1415 return; 1416 combchars[i]->prev = i; 1417 combchars[i]->next = i; 1418 }
Exploitable or not, it would be annoying if someone stuffed this into logfiles being tailed, or whatever.
Tavis.
– _o) $ lynx lock.cmpxchg8b.com /\\ _o) _o) $ finger taviso@…org _\_V _( ) _( ) @taviso
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.