0 byte write heap buffer overflow in start_decoder in stb_vorbis

published 2023-10-20 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-49965

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits: 0; none known

stb_vorbis is a single file MIT licensed library for processing ogg vorbis files. A crafted file may trigger out of bounds write in `f->vendor[len] = (char)'\0';`. The root cause is that if the len read in `start_decoder` is `-1` and `len + 1` becomes 0 when passed to `setup_malloc`. The `setup_malloc` behaves differently when `f->alloc.alloc_buffer` is pre-allocated. Instead of returning `NULL` as in `malloc` case it shifts the pre-allocated buffer by zero and returns the currently available memory block. This issue may lead to code execution.

Patch / fix

distros 1

stb Alpine 3.24, Alpine 3.23, Alpine 3.22 +3 more 0_git20231012-r0

alpine advisories ALPINE-CVE-2023-45675

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

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 2 y ago (2024-09-12)

Exploit prediction

0.74% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
NVD	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

nothings stb

Classification

Weakness

CWE-787 Out-of-bounds Write

References

Sources

CVE List CVE-2023-45675
NVD CVE-2023-45675

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.

Summary