Medium [CVE-2026-55892] Denial of Service via crafted spell file
This medium-severity Red Hat Linux advisory covers CVE-2026-55892 affecting Red Hat Hardened Images, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6.
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Summary
Vim is an open source, command line text editor. Prior to 9.2.0662, the dump_prefixes() function in src/spell.c walks a spell-file prefix trie iteratively with a depth counter while dumping the prefixes that apply to a word.
The counter is bounded only by the trie structure itself; it is never checked against the size of the fixed MAXWLEN-element stack arrays it indexes (prefix[], arridx[], curi[]). A crafted.spl file, loaded when the user dumps the word list, can drive the descent arbitrarily deep, so the function writes past the end of those arrays.
This is a stack out-of-bounds write that corrupts the call frame and crashes the editor. This vulnerability is fixed in 9.2.0662.
A remote attacker could exploit this vulnerability by convincing a user to load a specially crafted spell file. This leads to a Denial of Service (DoS), making the editor unavailable to the user.
A flaw was found in Vim's spell file handling. The dump_prefixes() function in src/spell.c does not validate the depth of the prefix trie against the size of fixed-size stack arrays, allowing a crafted.spl file to cause a stack out-of-bounds write and crash.
Red Hat ships Vim in all RHEL versions and OpenShift CoreOS. Exploitation requires a user to load a malicious spell file and run:spelldump or spelling completion.
Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).
- < 9.2.0662
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
- 9.2.0662
- vim-main-9.2.780-1.hum1
- RHSA-2026:35387
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Mitigation checklist
- Do not load untrusted spell files (.spl) from unknown sources. Avoid using :spelldump with spell files of unknown provenance.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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