crypto/x509/pkix: avoid quadratic string concatenation in RDNSequence.String by nsknv · Pull Request #78265 · golang/go

nsknv · 2026-03-21T01:05:37Z

RDNSequence.String builds its result using repeated s += ... inside
nested loops, leading to O(N²) time and memory complexity.
A certificate with many Subject or Issuer RDN entries can therefore
cause excessive CPU and memory usage when String is called.

Switch to strings.Builder to construct the output, reducing complexity
to O(N) without changing behavior.

This follows the same approach used to fix CVE-2025-61729
(HostnameError.Error), which addressed the same quadratic concatenation
pattern.

gopherbot · 2026-03-21T01:29:19Z

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gopherbot · 2026-03-21T01:38:06Z

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gopherbot · 2026-03-21T01:46:56Z

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gopherbot · 2026-03-26T19:04:50Z

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Patch Set 1: Code-Review+1

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gopherbot · 2026-03-26T19:04:51Z

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Patch Set 1:

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gopherbot · 2026-03-26T19:14:59Z

This PR (HEAD: 989d61d) has been imported to Gerrit for code review.

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gopherbot · 2026-03-26T19:34:37Z

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Patch Set 1: Code-Review+1

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gopherbot · 2026-03-26T20:05:35Z

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….String RDNSequence.String builds its result using repeated s += ... inside nested loops, leading to O(N²) time and memory complexity. A certificate with many Subject or Issuer RDN entries can therefore cause excessive CPU and memory usage when String is called. Switch to strings.Builder to construct the output, reducing complexity to O(N) without changing behavior. This follows the same approach used to fix CVE-2025-61729 (HostnameError.Error), which addressed the same quadratic concatenation pattern.

gopherbot · 2026-03-26T21:05:30Z

This PR (HEAD: b0706c2) has been imported to Gerrit for code review.

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The title and description of the GitHub PR are used to construct the final commit message.
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gopherbot · 2026-03-26T21:27:00Z

Message from Navtej Kathuria US:

Patch Set 3: Code-Review+1

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gopherbot · 2026-03-26T22:04:38Z

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Patch Set 3: Code-Review+2 Commit-Queue+1

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gopherbot · 2026-03-26T22:04:39Z

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gopherbot · 2026-03-26T22:04:39Z

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Patch Set 3: Code-Review+2

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gopherbot · 2026-03-26T22:32:20Z

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gopherbot · 2026-03-26T22:32:21Z

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gopherbot · 2026-03-26T22:32:21Z

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gopherbot · 2026-03-27T00:35:26Z

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gopherbot · 2026-04-03T02:05:50Z

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gopherbot · 2026-04-03T14:33:05Z

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gopherbot · 2026-04-03T14:33:06Z

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gopherbot · 2026-04-03T14:33:06Z

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….String RDNSequence.String builds its result using repeated s += ... inside nested loops, leading to O(N²) time and memory complexity. A certificate with many Subject or Issuer RDN entries can therefore cause excessive CPU and memory usage when String is called. Switch to strings.Builder to construct the output, reducing complexity to O(N) without changing behavior. This follows the same approach used to fix CVE-2025-61729 (HostnameError.Error), which addressed the same quadratic concatenation pattern. Change-Id: Id44303b5732081de9f01d186bc2b8ac66349a650 GitHub-Last-Rev: b0706c2 GitHub-Pull-Request: #78265 Reviewed-on: https://go-review.googlesource.com/c/go/+/757680 Reviewed-by: Navtej Kathuria US <nkathuria@nvidia.com> Reviewed-by: Daniel McCarney <daniel@binaryparadox.net> Reviewed-by: Roland Shoemaker <roland@golang.org> Reviewed-by: Mateusz Poliwczak <mpoliwczak34@gmail.com> Reviewed-by: Junyang Shao <shaojunyang@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Mateusz Poliwczak <mpoliwczak34@gmail.com>

gopherbot · 2026-04-03T20:32:10Z

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Patch Set 3: Code-Review+1

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gopherbot · 2026-04-03T20:41:43Z

This PR is being closed because golang.org/cl/757680 has been merged.

nsknv · 2026-04-06T18:20:51Z

PR is merged, reference: 493731943

nsknv force-pushed the fix-rdnsequence-quadratic branch from 90b83e4 to 989d61d Compare March 26, 2026 19:13

nsknv changed the title ~~crypto/x509/pkix: use strings.Builder in RDNSequence.String()~~ crypto/x509/pkix: avoid quadratic string concatenation in RDNSequence.String Mar 26, 2026

nsknv force-pushed the fix-rdnsequence-quadratic branch from 989d61d to b0706c2 Compare March 26, 2026 21:00

gopherbot closed this Apr 3, 2026

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