A heap buffer overflow vulnerability was discovered in Perl.
Release branches 5.34, 5.36, 5.38 and 5.40 are affected, including development versions from 5.33.1 through 5.41.10.
When there are non-ASCII bytes in the left-hand-side of the tr operator, S_do_trans_invmap can overflow the destination pointer d.
$ perl -e $_ = x{FF} x 1000000; tr/xFF/x{100}/;
Segmentation fault (core dumped)
It is believed that this vulnerability can enable Denial of Service and possibly Code Execution attacks on platforms that lack sufficient defenses.
Weakness
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Perl |
Perl |
5.33.1 (including) |
5.38.4 (excluding) |
| Perl |
Perl |
5.39.0 (including) |
5.40.2 (excluding) |
| Perl |
Perl |
5.41.0 (including) |
5.41.10 (including) |
| Perl |
Ubuntu |
jammy |
* |
| Perl |
Ubuntu |
noble |
* |
| Perl |
Ubuntu |
oracular |
* |
| Perl |
Ubuntu |
plucky |
* |
| Perl |
Ubuntu |
upstream |
* |
Potential Mitigations
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
- D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
- Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
- Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
- For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].
References