PT-2026-51880 · Linux · Linux
Publicado
2026-06-24
·
Atualizado
2026-06-24
·
CVE-2026-52986
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In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf conntrack sip: don't use simple strtoul
Replace unsafe port parsing in epaddr len(), ct sip parse header uri(),
and ct sip parse request() with a new sip parse port() helper that
validates each digit against the buffer limit, eliminating the use of
simple strtoul() which assumes NUL-terminated strings.
The previous code dereferenced pointers without bounds checks after
sip parse addr() and relied on simple strtoul() on non-NUL-terminated
skb data. A port that reaches the buffer limit without a trailing
character is also rejected as malformed.
Also get rid of all simple strtoul() usage in conntrack, prefer a
stricter version instead. There are intentional changes:
-
Bail out if number is > UINT MAX and indicate a failure, same for too long sequences. While we do accept 05535 as port 5535, we will not accept e.g. 'sip:10.0.0.1:005060'. While its syntactically valid under RFC 3261, we should restrict this to not waste cycles when presented with malformed packets with 64k '0' characters.
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Force base 10 in ct sip parse numerical param(). This is used to fetch 'expire=' and 'rports='; both are expected to use base-10.
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In nf nat sip.c, only accept the parsed value if its within the 1k-64k range.
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epaddr len now returns 0 if the port is invalid, as it already does for invalid ip addresses. This is intentional. nf conntrack sip performs lots of guesswork to find the right parts of the message to parse. Being stricter could break existing setups. Connection tracking helpers are designed to allow traffic to pass, not to block it.
Based on an earlier patch from Jenny Guanni Qu qguanni@gmail.com.
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