What is CVE-2015-5523?

CVE-2015-5523 is a vulnerability in Apple Iphone OS, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2015-08-11.

Is CVE-2015-5523 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Apple Iphone OS

CVE-2015-5523

The ParseValue function in lexer.c in tidy before 4.9.31 allows remote attackers to cause a denial of service (crash) via vectors involving multiple whitespace characters before an empty href, which triggers a large memory allocation.

Vulnerability class: Buffer Overflow

Published 2015-08-11 · last modified 2026-06-17.

CVSS v2 metric

CVSS v2 base score 4.3 (Medium). Vector: AV:N/AC:M/Au:N/C:N/I:N/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.038 (89.8th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 90th percentile — 89.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.038 · newest: 0.038 · change: 0.000

Affected products

Apple Iphone OS
Apple Mac OS X
Apple watchOS
Htacg Tidy
Canonical Ubuntu Linux — versions 12.04, 14.04, 15.04
Debian Linux — versions 7.0, 8.0

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

Public proof-of-concept exploits

mrash/afl-cve

References

www.securitytracker.com/id/1033703 (vdb-entry)
www.openwall.com/lists/oss-security/2015/07/13/7 (mailing-list, Exploit)
support.apple.com/HT205212 (Third Party Advisory)
lists.apple.com/archives/security-announce/2015/Sep/msg00008.html (vendor-advisory, Mailing List, Third Party Advisory)
www.openwall.com/lists/oss-security/2015/06/04/2 (mailing-list, Exploit)
www.ubuntu.com/usn/USN-2695-1 (vendor-advisory, Third Party Advisory)
support.apple.com/HT205267 (Third Party Advisory)
www.debian.org/security/2015/dsa-3309 (vendor-advisory, Third Party Advisory)
lists.apple.com/archives/security-announce/2015/Sep/msg00005.html (vendor-advisory, Mailing List, Third Party Advisory)
github.com/htacg/tidy-html5/issues/217 (Exploit)

Frequently asked questions

What is CVE-2015-5523?: CVE-2015-5523 is a vulnerability in Apple Iphone OS, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2015-08-11.
Is CVE-2015-5523 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.