# CVE-2026-89157: PCRE2 out-of-bounds write in pcre2_pattern_convert on 32-bit platforms

Source: https://junglewise.ai/threats/cve-2026-89157-pcre2-out-of-bounds-write-in-pcre2-pattern-convert-on-32-bit  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-89157 · Severity: medium · CVSS 5.7 · Published 2026-09-11

PCRE2 is a widely-used regular expression library integrated into many applications and systems. When processing very large patterns through the pattern conversion API on 32-bit systems, PCRE2 can allocate an undersized buffer and write beyond its bounds, causing crashes or potential memory corruption. This affects applications that accept untrusted regex patterns for conversion.

## Quick answers

**Is CVE-2026-89157 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-89157 being exploited in the wild.

**How severe is CVE-2026-89157?** Medium severity, with a CVSS score of 5.7, published 11 September 2026.

**Which products and versions are affected?** PCRE2Project PCRE2 10.30 through 10.47.

**Is there a fix for CVE-2026-89157?** A patch was published on 2026-08-31: Fixed in version 10.48 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-89157 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-89157?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A 32-bit integer overflow vulnerability exists in the pcre2_pattern_convert() function's automatic output allocation path. The vulnerability occurs when PCRE2-managed output allocation is requested (non-NULL buffptr with *buffptr == NULL) on 32-bit platforms. The affected code multiplies the converted pattern length by PCRE2_CODE_UNIT_WIDTH (a bit width, not a byte count), causing the multiplication to overflow and result in allocation of only the internal header (~12 bytes) while the function then writes a much larger converted pattern beyond the allocated buffer. The vulnerability requires an attacker to supply a very large foreign-syntax pattern to be converted; pattern compilation and matching are not involved. Fixed in PCRE2 10.48 via proper byte-size calculation and allocation overflow checks.

## Affected products

- PCRE2Project PCRE2 10.30 through 10.47

## Timeline

- 2026-08-31: disclosed
- 2026-08-31: patched: Fixed in version 10.48

## References

- [https://github.com/PCRE2Project/pcre2/releases/tag/pcre2-10.48](https://github.com/PCRE2Project/pcre2/releases/tag/pcre2-10.48)
- [https://github.com/PCRE2Project/pcre2/security/advisories/GHSA-q8g2-wprr-34m9](https://github.com/PCRE2Project/pcre2/security/advisories/GHSA-q8g2-wprr-34m9)