CVE-2026-103658: Heap Overflow (CVSS 5.9)

Description

GNU Aspell 0.60.8.2 (first vulnerable version is not known) contains a heap-based buffer overflow write (CWE-122) in its read-only dictionary loader. String::reserve() in common/string.hpp computes its capacity check with a signed int ((int)s + 1), so a requested size of 0x7FFFFFFF wraps negative and the backing buffer is never grown. ReadOnlyDict::load() in modules/speller/default/readonly_ws.cpp passes the unvalidated 32-bit size fields from a .rws dictionary header into this path, so a crafted .rws file with a valid endian marker (12345678) and an oversized length field (e.g. lang_name_size = 0x7FFFFFFF) causes attacker-controlled data to be written out of bounds past an undersized heap allocation. An attacker who induces a victim to load a malicious dictionary — for example via aspell dump master <file> — can corrupt heap memory, resulting in denial of service and potentially code execution. Fixed in b830b6e and will be fixed in release 0.60.8.3.

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CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-122 CWE-122

References

Other References

https://github.com/GNUAspell/aspell/security/advisories/GHSA-p35p-2mw5-fj5j https://github.com/GNUAspell/aspell/security/advisories/GHSA-p35p-2mw5-fj5j

Frequently Asked Questions

What is CVE-2026-103658? +

GNU Aspell 0.60.8.2 (first vulnerable version is not known) contains a heap-based buffer overflow write (CWE-122) in its read-only dictionary loader. String::reserve() in common/string.hpp computes its capacity check with a signed int ((int)s + 1), so a requested size of 0x7FFFFFFF wraps negative and the backing buffer is never grown. ReadOnlyDict::load() in modules/speller/default/readonly_ws.cpp passes the unvalidated 32-bit size fields from a .rws dictionary header into this path, so a crafted .rws file with a valid endian marker (12345678) and an oversized length field (e.g. lang_name_size = 0x7FFFFFFF) causes attacker-controlled data to be written out of bounds past an undersized heap allocation. An attacker who induces a victim to load a malicious dictionary — for example via aspell dump master <file> — can corrupt heap memory, resulting in denial of service and potentially code execution. Fixed in b830b6e and will be fixed in release 0.60.8.3. It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-103658? +

CVE-2026-103658 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-103658? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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