Description
In PHP 8.3.* before 8.3.5, function mb_encode_mimeheader() runs endlessly for some inputs that contain long strings of non-space characters followed by a space. This could lead to a potential DoS attack if a hostile user sends data to an application that uses this function.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| PHP Group | PHP | 8.3.* – < 8.3.5 | 8.3.5 |
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.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | php8.3 | 8.3.6-0maysync1 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | php8 | 8.3.6-1.1 | openSUSE-SU-2024:13867-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | php83 | 8.3.5-r0 | — |
| Alpine v3.23 | php83 | 8.3.5-r0 | — |
| Alpine v3.22 | php83 | 8.3.5-r0 | — |
| Alpine v3.21 | php83 | 8.3.5-r0 | — |
| Alpine v3.20 | php83 | 8.3.5-r0 | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | php83 | 8.3.6-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | php | 8.3.6-1 | — |
Advisories 2
- WID-SEC-2024-0867 PHP: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 21, 2026
- openSUSE-SU-2024:13867-1 php8-8.3.6-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026