CVE-2026-8829

Description

HTML::Entities versions before 3.84 for Perl read freed heap memory in _decode_entities. The XS routine backing HTML::Entities::_decode_entities cached a pointer (repl) into the entity-value SV returned by hv_fetch on the entity2char hash. When the input SV was identical to a value SV in that hash, and that value contained its own key as an entity reference, a later call to grow_gap() reallocated the SV's PV buffer and freed the backing allocation that repl still pointed into. The subsequent copy loop read repl_len bytes from the freed allocation. The read may disclose adjacent heap contents into the destination SV.

CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0031

Probability of exploitation

0.23%

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-416 Use After Free

Affected Products

Vendor	Product	Versions
oalders	html\	< 3.84

References

Advisories & Patches

https://github.com/libwww-perl/HTML-Parser/commit/6922552b0778c90a9587a3894e248be4d3a25e1c.patch https://github.com/libwww-perl/HTML-Parser/pull/56

Other References

http://www.openwall.com/lists/oss-security/2026/06/04/2

Frequently Asked Questions

What is CVE-2026-8829? +

HTML::Entities versions before 3.84 for Perl read freed heap memory in _decode_entities. The XS routine backing HTML::Entities::_decode_entities cached a pointer (repl) into the entity-value SV returned by hv_fetch on the entity2char hash. When the input SV was identical to a value SV in that hash, and that value contained its own key as an entity reference, a later call to grow_gap() reallocated the SV's PV buffer and freed the backing allocation that repl still pointed into. The subsequent copy loop read repl_len bytes from the freed allocation. The read may disclose adjacent heap contents into the destination SV. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-8829? +

CVE-2026-8829 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0031, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-8829? +

CVE-2026-8829 affects products from oalders, specifically: html\. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-8829? +

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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