Subject: pgsql: Protect against small overread in SASLprep validation

From: Jacob Champion <[email-masked]>
Date: Fri, 06 Feb 2026 20:20:11 +0000

Protect against small overread in SASLprep validation

(This is a cherry-pick of 390b3cbbb, which I hadn't realized wasn't
backpatched. It was originally reported to security@ and determined not
to be a vulnerability; thanks to Stanislav Osipov for noticing the
omission in the back branches.)

In case of torn UTF8 in the input data we might end up going
past the end of the string since we don't account for length.
While validation won't be performed on a sequence with a NULL
byte it's better to avoid going past the end to beging with.
Fix by taking the length into consideration.

Reported-by: Stanislav Osipov <[email-masked]>
Reviewed-by: Daniel Gustafsson <[email-masked]>
Discussion: https://postgr.es/m/CAOYmi+mTnmM172g=[email-masked]
Backpatch-through: 14

Branch
------
REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/46aaec4c0e6d90e9f074982feb43efd4b3c42a78

Modified Files
--------------
src/common/saslprep.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)